Goldfish Cloudy Eye (s): Causes, Symptoms & Treatments [with Pictures]

goldfish cloudy eye

Cloudy eye(s) in goldfish is not a disease but a condition caused by a wide variety of possible underlying problems. Unfortunately, goldfish can’t tell us what’s wrong, so it’s up to us goldfish parents to figure out the cause and find an appropriate treatment. 

This condition can be a serious symptom of bacterial infection and parasites – particularly when the cloudiness is on both eyes. Of course, when a single eye is infected or damaged, it can still indicate something is wrong.

Don’t panic! In our experience, many goldfish can successfully recover from a cloudy eye by following the proper treatment plan. 

What is Cloudy Eye(s) in Goldfish?

Usually, a cloudy eye involves the cornea (the transparent outer covering of the pupil) of the goldfish becoming inflamed or accumulating excessive tissue fluid behind one or both eyes [1], giving it a cloudy, opaque, or swollen appearance. 

In some cases, depending on the goldfish varieties and severity of the illness, the fish may show other physical symptoms and behavioral changes, such as bulging eyes, clamped fins, lethargy, buoyancy problems, etc. 

Fancy Goldfish with Protruding Eyes

Bubble Eye Goldfish has protruding eyes

Fancy goldfish refers to different varieties of goldfish (Carassius Auratus) that have been specifically bred to develop certain physical characteristics. 

Some have enhanced body colors or shapes, some come in flowy double tails, and some are known for their naturally protruding eyeballs. Of course, this is definitely not the Popeye disorder.

While goldfish varieties with protruding eyes, like telescope-eye goldfish (Red Moor Goldfish) and Bubble Eye Goldfish, can be a beautiful sight to behold, they are also more susceptible to developing cloudy eyes due to their large, delicate eyes are prone to cuts, and tears from tank decorations and tank mates.

What Causes Goldfish Cloudy Eye?

Based on years of experience, the cloudy eye goldfish can be due to physical trauma, bacterial infection, parasites, and water quality issues. 

Like Popeye, the cloudy eye disorder in goldfish may be unilateral (a single eye) or bilateral (both eyes).

When only one eye appears cloudy, it’s more likely associated with trauma rather than an infection and poor water quality. Luckily, in this case, the cloudy eye will eventually go away as it heals.

If both eyes are affected, some infections and/or water quality issues may be blamed. It’s critical to identify the underlying cause and take appropriate action, or it will cause the fish to die. 

Water Quality Issues

Poor water quality is one of the most common causes of goldfish illness and death. Goldfish are messy eaters and poopers. This means goldfish tanks can become very dirty rather quickly if not maintained properly. 

Among these important water parameters, ammonia levels and water temperature are mainly responsible for the cloudy eye in goldfish.

Ammonia Poisoning

Ammonia Poisoning in goldfish

As you may already know, ammonia poisoning usually occurs when you first set up a goldfish tank, but it can also happen in a “mature” aquarium due to the poor functioning of the nitrogen cycle, where ammonia formed from fish waste and uneaten food is converted by beneficial bacteria into nitrite, then nitrate, and finally back to air.

When ammonia gets too high due to overfeeding or overpopulation, your fish’s eyes may appear cloudy; however, this is less noticeable than the following signs.

Red or purple gills
Bloody patches or streaks on the body
Ragged or frayed fins
Laying at the bottom of the tank
Difficulty breathing
Loss of appetite
Uncycled aquarium
Chemically treated tap water
Increased fish byproducts
Overstocking & Overfeeding
Incorrect pH levels


It’s important to note that ammonia poisoning can be fatal to goldfish, so prompt action is critical. The first step is to test the ammonia level with a standard test kit. If the reading rises above 1 ppm, start treatment immediately by following these steps:

  1. Reduce ammonia levels: Perform a partial water change (50% or more) to dilute the toxic ammonia levels in the aquarium.
  2. Improve water quality: Add a high-quality aquarium water conditioner to remove chlorine, chloramines, and heavy metals from tap water.
  3. Add bacteria: Add a bacteria supplement to the aquarium to establish a healthy biological filter.
  4. Increase aeration: Increase the aeration in the aquarium by adding an air stone or increasing the power of the existing air pump.

Gas Bubble Disease (GBD)

Gas Bubble Disease in goldfish

Gas Bubble Disease (GBD) in goldfish is a condition that results from gas supersaturation [2], leading to symptoms such as small bubbles trapped within a fish’s eye or tissues. 


In GBD, the most obvious sign is the presence of small bubbles behind or inside the eye, though they may also be found in other parts of the body, such as fin rays and operculum (gill openings).


  • Cracked or loosely connected pipe or filtration component.
  • Sudden changes in water temperature.
  • A sudden rise in pressure.
  • Abundant algae growth in ponds


To treat GBD, it is essential to determine the source of the excess gases. Check the pipes, filters, and water temperature. Never try to burst the bubbles, as this will often bring secondary bacterial infection.

Physical injury

As mentioned, some varieties with protruding eyes are vulnerable to abrasion that can cause localized inflammation. As a result, you may notice your goldfish’s eye turn cloudy or exophthalmic (popped out), depending on the level of the injury.

There is no treatment for traumatic eye injuries in fish. Preventative measures such as providing a safe environment with smooth surfaces, clean water, and silk aquarium plants are essentialial.

Bacterial Infection

Goldfish frequently develop cloudy eyes as a result of bacterial infections. If both eyes are cloudy and swollen, it’s likely that bacterial infections are present.

Virtually the root causes of bacterial infections are related to poor water conditions in the aquarium.

Streptococcus spp.

Although most aquarium bacterial infestations are Gram-negative, fish eye disorders are usually caused by Gram-positive bacteria, specifically Streptococcus species or related bacteria, including Lactococcus, Enterococcus, and Vagococcus [3]. 

Streptococcal (often shortened to Strep) outbreaks can cause high mortality rates (> 50%) over a period of 3 to 7 days. Unlike most common opportunistic fish bacteria, such as Aeromonas or Columnaris, Strep can be more aggressive and even fatal.


The noticeable sign of Strep disease is usually cloudy eyes (corneal opacity-whitish eyes). You may see a variety of other signs of illness as well.

  • Enlarged eyes (exophthalmos)
  • Hemorrhages in the eye, gills, or the base of the anal fin
  • Excess mucus
  • Difficulty swimming
  • Lethargy
  • Darkened coloration


For moderate Strep infections, a hospital tank with API® E.M. Erythromycin (Erythromycin Phosphate) will work. In severe cases, Seachem NeoPlex used in a medicated food mix is recommended. 

Aeromonas spp.

Goldfish and koi are the most popular cold-water fishes, which are susceptible to Viral Hemorrhagic Septicemia (VHS), a highly infectious and lethal virus caused by the Aeromonas species.

Aeromonas is a group of Gram-negative, facultative anaerobic bacteria, with A. salmonoid (commonly called Furunculosis) and A. hydrophila being among the best-known species. Both species are causative agents to be linked to causing hemorrhagic streaks or ulcers in the fins, tail, gills, and skin.


Hemorrhages may also be seen in the internal muscle and organ tissues. In some instances, goldfish may exhibit other signs such as exophthalmia (pop-eye), cloudy eyes, ascites (distended abdomen), discoloration, abnormal swimming behavior, and loss of appetite.


Given the fact that Aeromonas are Gram-negative, facultative anaerobic bacteria, treatment is currently limited to antibiotics. However, treating them in cold water (below 65°F) can be challenging as many antibiotics lose efficacy.

Seachem KanaPlex (Kanamycin), a Gram-negative antibiotic, mixed with fish food, has proved to be effective in treating Aeromonas infection.


Many types of protozoan parasites can also contribute to cloudy eyes in goldfish. They enter your fish pond or aquarium are the result of failure to quarantine new fish, plants, or other decorations.

The most common of these are:

Epistylis spp.

Epistylis in goldfish

Several Epistylis species (ciliated freshwater protozoan) are known to infect the skin, fins, and gills, resulting in irregular white spots on the fish’s eyes and other body parts. Epistylis in cold water fish is not common but may break out during the warmer months.


Epistylis infestation is often confused with ich due to similar white spots on the skin. However, it can be differentiated by the irregular shape and translucent coloration of the spots.


Maracyn 2 or Kanaplex medicated fish food can be effective. However, to kill the Epistylis on the fish’s eggs, the tank should be treated with Malachite green.

Eye Flukes (Diplostomum spathacaeum)

The eye fluke (Diplostomum spathacaeum) [4] is a microscopic parasite that can infect warm-water and cold-water fishes. Occasionally, tiny worms can be seen wriggling around in the goldfish’s eyes. These parasites can be tough to eradicate, as they often invade the fish’s eye lenses, where they are protected from the host’s immune system.


The infected goldfish often have enlarged and cloudy eyes.

As the parasite replicates and spreads, the goldfish will generally become blind in the infected eye, affecting its feeding and growth.


Unfortunately, there is no effective treatment currently available to treat eye flukes. 


Another serious but uncommon eye disorder that goldfish can suffer from is cataracts. This condition occurs when the lens of the eye becomes cloudy or opaque, reducing the vision of the fish. This can be caused by various factors, including genetics, injury, infection, or old age. There is also no known treatment or cure for goldfish cataracts.

In conclusion

Goldfish cloudy eye(s) can be caused by several factors and should always be addressed as soon as possible. Treatment options include antibiotics, parasite medications, and supportive care.

Unfortunately, cataracts and eye flukes are untreatable and may cause permanent vision loss.

For a successful treatment, always consult your aquatic veterinarian for the best recommendations. They can provide personalized advice for goldfish care and treatment when needed.

Good luck!

Article Sources:

  1. Aitchtuoh, Fischer. Treating Pop-Eye. Central Florida Aquarium Society
  2. Effects of Total Dissolved Gas Supersaturation in Fish of Different Sizes and Species. National Library of Medicine
  3. Streptococcal Infections of Fish. University of Florida
  4. Diplostomum spathacaeum. Wikivet

Can Bala Shark and Rainbow Shark Live Together? (No! Because of Aggression)

bala shark and rainbow shark

While both the Rainbow Shark and the Bala Shark are stunning in an aquarium, there are a lot of factors to consider if you are looking at having them in the same tank. 

Their fully-grown size, behavior, and other aspects are key when considering having Bala Sharks and Rainbow Sharks live together. Keep reading to find out more information about whether it is recommended to have both of these fish living together.

Can Bala Shark and Rainbow Shark Live Together?

Bala Sharks can live peacefully with many other tropical fish; however, it is a different story for Rainbow Sharks. Rainbow Sharks, in many cases, tend to show aggression towards other similar shark and fish species, including the Bala Shark. 

Because of this, it is not recommended to have Rainbow Sharks and Bala Sharks in the same tank.

Rainbow Sharks may also chase or even attack their own species if there is more than one kept in a tank. However, Rainbow Sharks can be placed with other tropical fish in the same tank as long as they are not (or do not appear) to be of the same species. 

Species Overview: Bala Shark Vs. Rainbow Shark

The Bala Shark, or Balantiochelios melanopterusis part of the Cyprinidae family. This family includes carps and minnows, which means that the Bala Shark name is a bit of a misnomer and is not actually considered to be a shark.

It may also be called the Tricolored Shark or Tricolored Minnow when you find them in stores. And because the juvenile fish may be only 3-4 inches, one might think that these fish do not grow very large. However, Bala Sharks can quickly increase in size and outgrow most standard tanks. 

Another thing to keep in mind is that many pet stores will not accept full-grown Bala Sharks back, as they can reach 13 inches (35 cm), which is too large for their tanks. So it is a good idea for you to do your research before selecting Bala Sharks and to make sure that your tank is large enough to accommodate them into maturity.

The Rainbow Shark (Epalzeorhynchos frenatum), sometimes referred to as the whitefin shark or ruby shark, is also part of the Cyprinidae family, meaning it is not considered a true shark as well. These do not grow as large as Bala Sharks, and typically only reach 6 inches (15 cm) in length.

Common Names:Bala Shark, hangus, Malaysian shark, silver bala, silver shark, tricolor shark, tri-color shark minnowRainbow Shark, ruby shark, red-fin shark, red-finned shark, rainbow sharkminnow, green fringelip labeo, whitefin shark and whitetail sharkminnow
Scientific Name:Balantiocheilos melanopterusEpalzeorhynchos frenatum
Origin:Southeast AsiaSoutheast Asia
Max Size:13 inches (35 cm)6 inches (15 cm)
Social:Peaceful schooling fish but may eat small fish.Peaceful juveniles, but adults can be aggressively territorial towards other similarly shaped.
Care:Easy to intermediate.Intermediate
Lifespan:10 years15 years
pH:6 to 86 to 8
Temperature:72 to 82 F (22 to 28 C)75 to 81 F (24 to 27 C)
KH: 5 to 12 dGH5 to 11 dGH
Tank Level:All levelsBottom to mid levels
Breeding:Egg-layer, is difficult in a home aquarium setting. Egg-layer, is difficult in a home aquarium setting.
Tank Size (Minimum)120 gallons50 gallons or 55 gallons

Behavior and Temperament

The main reason why it is not recommended to keep these two fish together, is because Rainbow Sharks have a tendency to act aggressively towards other similar species. However, the Rainbow Shark can be placed with other tropical fish species, such as barbs, and can live quite happily in an aquarium.

Interestingly, in the wild, Rainbow Sharks are not known to be aggressive with their own kind, however, tend to be more aggressive when placed into a home aquarium environment. 

While both fish are considered to be omnivores, it is also generally not a good idea to place Rainbow Sharks with any timid or small creatures, as they may act territorial and chase or even eat the smaller and slower fish. This may also create a stressful environment for the other inhabitants of your aquarium. 

Bala Sharks, on the other hand, can usually get along quite well in most aquariums and prefer to school with others of their kind. Be cautious though, as they eat shrimp and snails, and even smaller fish, and as mentioned above, they may grow too large for most household tanks. 

Fish Size, Age, and Gender

Bala sharks can grow up to 14 inches (35.5 cm), making them a large addition if you are looking to keep them in a tank. Also, they have a fairly long lifespan, with some Bala Sharks living to be 10 years old. Females and males of the species look similar in most instances, and can be difficult to tell apart even once they are grown. 

Bala Sharks are typically silver, with black marks on their fins. Rainbow Sharks bodies can be black or a variation of blue. Their fins are typically orange in color, making them a striking addition to aquariums. Rainbow Sharks grow quite a bit smaller than Bala Sharks, with an average grown length of 6 inches (15cm). 

There are also more variations between the Rainbow Shark females and males, as the males are typically thinner, with their tail fins hosting a more dark coloration than their female counterparts. These fish can live up to 8 years.

Tank Size and Dimension

As the size of the Balas can be quite large, and also because they do better in schools, it is suggested a tank that is at least 125 gallons would be necessary for multiple Bala Sharks. Some pet owners have also remarked that Bala Sharks may try to jump out of tanks, so having a lid for your aquarium is highly encouraged.

Rainbow Sharks are more modest and may be housed in a tank of 50 gallons. Rainbow Sharks can be helpful as they may clean up your tank by eating built-up algae off of the sides.


A school of bala shark

As mentioned above, Bala Sharks like to be with their own kind, and groups of 3 or more are preferred. 

Rainbow Sharks, on the other hand, should be kept as the only one of its species in a tank, or else may exhibit aggression towards their lookalikes. But when paired with fish such as barbs, cichlids, catfish, and gouramis can do quite well in a modest aquarium.

Water Conditions 

Both species in their natural habitat come from Southeast Asia, basically they share the same preferences for water conditions. However, Bala Sharks are slightly hardy and, in most cases, can withstand changes better than Rainbow Sharks.


Not much information is found on Bala Sharks being able to be bred in tanks, outside of the use of hormones for commercial breeding. They do lay eggs but have not been able to reproduce in an aquarium setting.

The same can be said for Rainbow Sharks; though they are also known to lay eggs, it is difficult to find information on the successful breeding of those kept in an aquarium.


In short, the Bala Shark and the Rainbow Shark should not be housed together due to the Rainbow Sharks possible aggressiveness. There is also an issue of tank size and schooling with the Bala Shark that needs to be considered, as Bala Sharks can grow over a foot long and like to be with similar species. 

In conclusion, Rainbow Sharks overall are not recommended to be in a tank with any similar species or fish that looks similar to them, as they can become territorial and attack their relatives. 

Red Spots On Goldfish: Symptoms, Causes & Treatments

Red Spots On Goldfish

Goldfish are one of the most common, friendly fish you can have in your aquarium. However, they are prone to conditions like red spots.

If you are wondering why there are red spots on goldfish and how to cure it, you’ve come to the right place. In this guide, we will discuss all about red spots, why it occurs, medication, and how to treat it. 

So without delaying any further, let’s dive right in! 

Why Does My Goldfish Have Red Spots?

Three main factors can contribute to your goldfish developing red spots: red pest disease (hemorrhagic septicemia), enteric redmouth (ERM) disease, and ammonia poisoning. We will discuss all of these in detail below.

#1 Reason: Goldfish Red Pest Disease

Red Spots On Goldfish Caused by Goldfish Red Pest Disease

Red Pest, or hemorrhagic septicemia, is an acute, highly fatal [1] internal bacterial disease that affects goldfish and other freshwater fish, causing them to develop red, bloody streaks on their gills, eyes, bodies, and the base of the fins. 

Most bacteria that cause infections in fresh and marine fish fall into one of two groups: gram-positive or gram-negative [2], named for how they respond to gram staining.[3] Due to their different type of outer structures (cell walls), gram-positive bacteria appear purple to blue, and gram-negative bacteria stain pink to red. 

The difference between these two types of bacteria is important when trying to determine which antibiotics to use, as some only treat gram-positive bacteria while others are effective against gram-negative bacteria. Gram-negative bacteria tend to be more resistant to antibiotics.[4]

Gram-negative bacteria (GNB) are among the most significant pathogens of fish, including genera: Pseudomonas, Aeromonas, Flavobacterium, Vibrio, and Yersinia. Aeromonas species are often associated with hemorrhagic septicemia (Red Pest), and Flavobacterium columnare is the biggest culprit of columnaris disease in aquarium fish.

Hemorrhagic septicemia (red pest) is also highly contagious [5], making it difficult to treat and often leading to mass die-offs in aquariums and ponds. However, this bacterial disease has not been reported to infect humans, so there is no need to worry about handling your fish.

Signs of Red Pest Disease in Goldfish

Hemorrhagic Septicemia in goldfish
Photo: RatteryTattery

As the name suggests, the most common symptom of red pest disease in goldfish is red spots or streaks (hemorrhages) on the body, gills, and fins. In addition, fish may also display:

  • Pop eyes,
  • Bloated (fluid-filled) belly
  • Loss of coloration
  • Abnormal swimming behavior

From my first-hand experience, it can be difficult to diagnose an internal bacterial infection in goldfish. In most cases, goldfish infected with Hemorrhagic septicemia may show no signs of illness in its early stages, but the disease can still spread, leading to contagion. During the middle stage, you may notice scattered white spots or dots on the fish’s body and fins. However, if the disease is at a more advanced stage, your goldfish will develop more and more red streaks or spots on their bodies and fins. 

In some severe cases, the entire fish body may become covered in red sores and ulcers. Red pest is often fatal; even with treatment, the mortality rate can be as high as 80-100%.

Goldfish Red Pest Disease Causes

Interestingly, most bacteria that cause red pests or other diseases in fish, whether they belong to gram-positive or gram-negative, are actually normal inhabitants in the fish tank or pond and don’t usually cause problems in healthy fish.

These opportunistic pathogens take advantage and cause disease only when the fish’s immune system is not functioning properly. So, red pest disease is often seen as a secondary infection, following another underlying condition that has weakened the fish’s immune system.

Virtually all fish diseases can be traced to some form of stress factor, which weakens their immune system. The most common stressors that can lead to the fish disease include:

  • Poor water quality
  • Incorrect water chemistry
  • Inadequate filtration
  • Overcrowding
  • Poor diet
  • Injuries
  • Transportation stress
  • Leaving your aquarium lights on 24/7
  • Aggression from other tank mates

In addition, a goldfish with a weak immune system may be more prone to bacterial growth, further exacerbating the problem.

How Do You Treat Red Pest in Goldfish?

Goldfish Red Pest Disease

Since Hemorrhagic septicemia (red pest) is a very serious internal fish disease, external medications are not going to work, the only way to save your fish is through antibiotic treatment.

Author note: External remedies may help if the disease is in its early stages, but I’d recommend still using a broad-spectrum antibiotic instead.

It’s important to realize that antibiotics do not cure a fish. Instead, they merely suppress the growth of bacteria populations in your goldfish long enough for the fish’s immune system to recover and naturally eliminate bacteria. 

Making and Feeding Medicated Feed

The most effective way to treat red pest disease or other bacterial infections is to add antibiotics to the fish’s food. Generally, you can make your own medicated feeds by adding antibiotics to dry flake or making gelatin-based food. I highly favor the latter simply because it sinks rapidly.

  • Prepare 3 ounces (85 g) unflavored dry gelatin (like Knox gelatin)
  • Grind 1 ounce (28 g) of dry commercial fish food (pellets or flake) to a powder (similar size of the dry gelatin)
  • Mix the fish food and the gelatin powder together in a bowl
  • Add 1/2 ounce (1 tablespoon) of the antibiotic powder to the mixture. Avoid using stronger doses if the case isn’t severe, as their side effects can still cause harm. Stir well to ensure that the antibiotic powder is evenly distributed in the mixture.
  • Heat 2 cups of water to near boiling, then pour over 2 to 3 ounces of the mixture above while stirring constantly. The gelatin will dissolve, and the mixture will form a gel. You may add more hot water if the mixture appears too dry, while if it appears too wet, just add a small amount of dry mixture (typically not necessary). 
  • Spread the gelled mixture onto a silicone baking sheet or wax paper with even thickness. Allow the gel to cool and solidify in a refrigerator.
  • Once it’s cooled, you can cut the gel into small squares, put them into a plastic bag, and store them in the freezer until you’re ready to use them.

No products found.

Feed at least twice daily for at least ten days, offering the amount all your fish will completely consume in less than 3-5 minutes.

I would also recommend starving your fish a little before feeding them, and this will help encourage them to eat the medicated food.

Be aware that you should never use homemade medicated fish food more than ten days old. Freshness is key to success.

External Bath Treatment

An antibiotic feeding treatment can be accompanied by external bath and dip treatments using sulfa or nitrofurans drugs.

Nitrofurans are commonly used to treat ornamental fish, including nitrofurantoin, nitrofurazone, furanace, and furazolidone. The well-known drugs in this class are Seachem Focus and Hikari BiFuran

Three things to remember when using these drugs include:

  1. They are most effective against superficial bacterial skin infections because they do not penetrate the skin well.[6] Remove the fish from the bath immediately if you see any redness.
  2. Nitrofurans can be degraded by light, so the fish tank should be covered during the treatment.
  3. Nitrofurans are more toxic to fish than sulfa drugs.

Sulfonamides, or “sulfa drugs,” are the other broad-spectrum antibiotics used to treat bacterial infections. The better-known drugs with this ingredient include SeaChem SulfaPlex (69%), API Triple Sulfa, and Mardel Maracyn Plus. However, they are not as effective as they once were due to antibiotic abuse.

To treat a goldfish with sulfa or nitrofurans drugs bath, consider using five times the recommended dosage of the nitrofurans or ten times the recommended dosage of the sulfa drugs for only one hour every day. 

Continue bathing for at least three days after the symptoms have disappeared to ensure the infection does not recur.

If you have any questions, please consult a qualified aquarium veterinarian. As with any medication, use it as directed. Do not over-medicate, which can lead to health problems for your fish.

#2 Reason: Enteric Redmouth (ERM) Disease in Goldfish

Enteric Redmouth (ERM) Disease in Goldfish

Quite often, you’ll see red spots just on the goldfish’s mouth. This enteric redmouth disease is one of the particular viral hemorrhagic septicemia (VHS) caused by the bacterium Yersinia ruckeri.[7] 

As we’ve already mentioned in an earlier section, Yersinia ruckeri is a gram-negative bacteria. The bacterium enters the fish through the secondary gill lamellae, where it multiplies and quickly invades the fish’s blood and internal organs. Of course, it’s a serious infectious disease that will kill the goldfish if it’s not treated in time.

Signs of Redmouth Disease In Goldfish

Signs of Redmouth Disease In Goldfish

As its name suggests, this enteric redmouth disease can cause subcutaneous hemorrhages in the mouth, including gums, throat, and gums. The major clinic signs included:

  • Reddening of the mouth, opercula
  • Popeye (exophthalmia)
  • Discoloration
  • Inflammation of the jaws and palate
  • Blood red blotches at the base of fins
  • Thick yellow fluid in the intestine

Redmouth Disease Treatment

Treatment of redmouth disease is no different than treating any other bacterial infection in goldfish. You can use the same treatment for the red pest disease we’ve already mentioned.

#3 Reason: Ammonia Poisoning

Ammonia Poisoning vs Hemorrhagic septicemia (red pest)

The last common reason your goldfish have red spots might be ammonia poisoning, one of the biggest fish killers. Total ammonia in a fish tank is comprised of NH3 and NH4+. The former is extremely toxic to fish whereas the latter is not. However, as the water temperature or pH increases, the NH4+ shifts to NH3, toxic form.

Symptoms of Ammonia Poisoning in Goldfish

The high level of ammonia in the water makes it difficult for the fish to eliminate ammonia from their bodies [8], which will eventually cause stress, damage to the brain, gill, internal organs, and lead to death.

The signs of ammonia poisoning in goldfish include:

  • Gasping at the surface of the water for breath
  • Red or purple gills
  • Lethargy
  • Loss of appetite
  • Bloody patches on the body

As to the red gills, people often confuse it with the clinical sign of hemorrhagic septicemia (red pest). In fact, it’s quite easy to distinguish between the two. 

Red spots on goldfish gills caused by ammonia poisoning are internal, and they usually take on a deep red or purple color, not brownish red patches like those from hemorrhagic septicemia. Also, they don’t develop on the scales of the fish.


If you read that the ammonia level in your fish tank is above 1 ppm, you need to take the following emergency measures to lower it.

  • Do a 50% water change, and ensure the temperature of new and old water is the same.
  • Use reverse osmosis (RO) water to lower the pH
  • If the condition of your fish is still critical, you should use Amquel or Prime to remove ammonia.
  • For fish exposed to high ammonia levels, you need to quarantine them in a hospital tank and treat them with antibiotics.

Final Thoughts 

Well, now that you are up to date with all the information about red pest disease in goldfish, we can end our guide here. 

Remember that the most common cause for this disease is unsanitary tank conditions. So, make it a point to purchase a water testing kit that will help you determine the water quality of your tank. 

Furthermore, ensure that you keep the tank clean at all times and maintain a healthy diet for your goldfish to thrive. And that’s all we have for you today; do take good care of your goldfish. 

Article Sources:

  1. Transcription profiles of skin and head kidney from goldfish suffering hemorrhagic septicemia with an emphasis on the TLR signaling pathway [NCBI]
  2. Use of Antibiotics in Ornamental Fish Aquaculture [UF]
  3. What is Gram Staining? [SERC]
  4. Molecular mechanisms of membrane targeting antibiotics [Sciencedirect]
  5. Fast Facts about Viral Hemorrhagic Septicemia [CFSPH]
  6. Evaluation of nitrofurazone baths in the treatment of bacterial infections of Sparus aurata and Oreochromis mossambicus [Sciencedirect]
  7. Yersinia ruckeri, the causative agent of enteric redmouth disease in fish [VeterinaryResearch]
  8. Aquarium Water Quality: Nitrogen Cycle []
  9. How To Make Medicated Feed [Hikariusa]
  10. 10.3.6. Red Blotches [aquariumscience]

How Big Do Koi Fish Get? (& How To Make Koi Grow Faster?)

How Big Do Koi Fish Get

The color and pattern of a koi fish can make it the star of any water body!

In fact, it’s their appearance that makes them a favorite among fish keepers and hobbyists around the world. But that doesn’t mean you can get one right now.

Unless you consider their size and weight, it’s practically impossible for you to provide them with the ideal thriving conditions. So, in today’s guide, we will answer a crucial question- how big do Koi fish get?

Let’s start!

How Big Do Koi Fish Get?

The exact length and weight of a koi fish depends on various factors like its genetics, the nutrition it receives, the population, and environment of the pond or aquarium. 

On average, they may grow anywhere between 20 and 24 inches long, weighing from 9 to 12 pounds. But some varieties can grow to be even longer and heavier. For instance, there was the “big girl” koi that weighed a mammoth 90 pounds and measured 40 inches long at the age of 17 years. 

For the better understanding of our readers, we have mentioned the different Koi varieties and their sizes in the following sections.

How Big Do Butterfly Koi Get? 

Also known as longfin koi or dragon carp, this variety can grow between 36 and 40 inches, with the most common size being 24 inches. However, they may weigh more than 20 pounds.

The body and fins of butterfly koi get pretty large, and they grow relatively slowly throughout their lifespan. If you plan to keep other fish with this variety, then make sure they don’t feed on the fins of the koi. 

How Big Do Japanese Koi Fish Get?

Perhaps, Japanese koi are the most famous variety due to their color, and they can grow between 22 and 26 inches long. Likewise, the average weight is 12 pounds, but some can grow to be heavier than that. Due to intensive and selective breeding, this variety tends to grow very fast in breeding farms.

How Big Do Domestic Koi Fish Get?

With the slowest growth rate among all the other varieties (due to genetics), domestic koi grow to be only 12 to 15 inches long, making them extremely suitable for home aquariums. 

How Big Do Jumbo Koi Fish Get?

As you may have guessed from the name, “jumbo” koi is the biggest and largest variety, measuring at least 30 inches long and weighing well over 20 pounds. 

On top of that, there are some larger jumbo varieties that may get about 36 inches long and weigh between 22 and 26 pounds. A few record-breakers have also grown up to 52 inches! So, they should always be housed in outdoor ponds with ample space and depth.

It’s also worth noting that jumbo koi is a selectively bred variety, and only a few chosen young koi receive the required intensive care to grow that big.

How Fast Do Koi Fish Grow Full Size?

Again, the exact growth rate of a Koi fish will depend on the variety that you have your eyes on. For instance, the smaller Koi carp will generally grow faster and may attain their full length in or under 2 years. 

However, larger varieties like the Japanese or jumbo koi can take 3 years to grow to their full length. In ideal conditions, all varieties should grow at least 6 to 8 inches long at the end of the first year.

That said, let’s take a look at the difference in the growth rate of koi in an aquarium and pond.

How Fast Do Koi Grow In An Aquarium?

With good water quality, temperature, and adequate nutrition, Koi fish can add about a little less than an inch per month. Or, in other words, they can become about 8 inches in 10 months.

Here, we should mention that keepers should always consider the maximum length of the koi variety that they wish to house in the aquarium. Although they won’t grow bigger than they are supposed to, it’s important to give them enough space and depth for free survival.

How Fast Do Koi Grow In Pond?

When it comes to rearing Koi in a pond, they usually grow about 5 inches long (average) each year. Now, some varieties may also add less than that, while others may add more than 5 inches in length per annum.

As they start attaining maturity, the growth rate (in terms of length) slows down and they start adding more girth to their bodies.It may also be helpful to know that koi fish will usually attain their maximum length at the end of the third or fourth year, depending on what variety you have opted for. And as they grow in length, they add weight, leading to bulkier and heavier bodies.

How To Make Koi Grow Faster?

Size Of Pond

Undoubtedly, one of the most important considerations is the size of the pond based on the koi variety and its final length. Smaller ponds will invariably make your koi struggle for space, stressing them out during their growth stage and preventing them from attaining the full size.

A full-sized jumbo koi may require up to 50 gallons of water in a pond that’s at least 3 feet deep. And the more koi you have, the more should the water and depth of the pond be. 

As a rule of thumb, keep 10 gallons of water per inch of koi fish. Additionally, consider the requirements of the other fish varieties, if any.

Proper Filtration

All fish varieties require good quality water, and koi fish is no exception. Bad quality water will put undue stress on koi, making them unhealthy, and even killing them before time. 

In this regard, we’d strongly recommend installing a 3-stage filtration system that can take care of mechanical, biological, and chemical filtration. 

While mechanical filtration will eliminate solid waste particles, biological filtration removes ammonia and nitrate compounds. And with chemical filtration, you can get rid of toxins, chemicals, or colors present in the water.

Moreover, the filtration system should process the entire water at least 3 to 5 times per hour.

Ideal Water Conditions

Koi thrive in ponds that have a pH level between 7 and 7.5, and the ideal water temperature should be around 70-degree Fahrenheit. Keep in mind that waste accumulation (like extra fish food and decaying vegetation) can alter the pH level. 

Besides, they are a resilient variety, so a water hardness level of around 80ppm (parts per million) should keep them healthy. You can get a water testing kit to monitor the water conditions on a regular basis.


Koi generally have a very fast metabolism rate, so they require feeding at least thrice a day. But in doing so, ensure that the quantity of food is such that they can finish it within 5 minutes per feed.

Talking about nutrition, they prefer a nice mix of proteins, vitamins, carbohydrates, and fats. Hence, you can feed them different things like peas, soybeans, melon, rice, shrimp, meat, lettuce, etc. 

However, their digestion can slow down significantly during winters, which is when you should switch to a low protein diet. It’s during the summer months that their metabolism hits the peak with a high need for a protein-based diet.

Balance Population

Given the size of most Koi fish varieties, it doesn’t come as a surprise that they need a lot of space, be it in the aquarium or pond. Overcrowding the water will hamper their growth, and it may even kill the younger ones.

Moreover, koi are typically a messy species, especially in overcrowded habitats. It won’t take them long to kill the “good” nitrifying bacteria, which acts as a natural filter for keeping biological waste like ammonia at bay to prevent the water from turning toxic.

In addition, they tend to swim at every level of the water and hibernate below the surface during winters. But overcrowding the pond or aquarium with too many koi or other fish varieties, for that matter, can put them under undue stress.

Koi Genetics

No matter how good the conditions and nutrition are, koi won’t grow taller or larger than what their genes allow. Japanese koi have high-quality genetics, and many breeders in the west have selectively bred this variety to create many modern domestic koi that can attain full maturity at the age of 2. 

Besides, their growth rate is at highest during the first year, which is a genetically defined feature.

Final Thoughts

That has brought us to the end of our guide today.

Although it can appear intimidating at first, rearing koi fish is actually a straightforward affair. But then again, every fish requires some maintenance effort, so there’s no shortcut here.

All you need to ensure is that they have enough food, space, and consistent good water quality. And don’t forget the bonding time, especially while feeding them. Trust us; the joy of your koi fish feeding directly out of your hands is second to none!

Until we meet again!

What Do Rainbow Sharks Eat?(3 Foods You Should Feed Your Fish)

What Do Rainbow Sharks Eat

Rainbow sharks may be one of the most brightly colored freshwater sharks, but they can be challenging to keep. One of the most important things to consider when owning a new rainbow shark is what you’ll feed them. Understanding what do rainbow sharks eat is essential as not all fish can eat all foods.

What Do Rainbow Sharks Eat in the Wild?

Just like humans, Rainbow Sharks thrive on a varied diet that’s closer to what they would be eating in the wild. The rainbow shark is a very versatile predator and has been found to be an omnivorous eater.

In the wild, they generally consume algae, decaying plants matter, as well as some live foods such as insect larvae, periphyton, and aquatic insects. As you can see, the weight of this diet is heavily dependent on vegetables. Yet protein found in insects and marine-based animals also plays a huge role in their nutrition.

What Should You Feed Your Rainbow Sharks in an Aquarium?

In captivity, their staple food should be very concentrated fish food that provides all their necessary nutrients in just a small amount per day, but this is far from the balanced diet that we are looking for. 

What exactly IS a balanced rainbow shark diet? 

In a short answer, a balanced rainbow shark diet includes high-quality fish food (flake & pellets), some real veggies, plus natural treats. 

The Staple Diet: Sinking Pellets or Flakes 

Although pellets or flakes may not be the most natural-looking choice, they are guaranteed to have all of their essential nutrients in one convenient bite-sized package! Compared with homemade fish food, they don’t tend to dissolve quickly in the tank water. The best fish food manufacturing companies formulate their products with the proper ratios of protein, fat, carbs, vitamins, and minerals to keep your sharks suffer from nutrient and vitamin deficiencies.

Considering their natural habitat, rainbow sharks tend to dwell near the bottom of your tank. For my albino rainbow shark, aside from he is feeding on what I add to the tank, he is constantly scavenging. I have fake plants that accrue algae on the leaves, and he will hover in place and clean every single leaf. These guys truly don’t get credit for what a good cleaner they are. He is constantly browsing for a free meal.

I like NSL Thera A+ 2mm sinking pellets because they contain high-quality proteins like squid, comes with extra garlic that can help fish resist stress better. What’s more, these pellets are preserved using natural preservatives, with no artificial preservatives, flavoring, or colors.

Pro tip: Instead of buying a huge jar of fish food for your rainbow shark, you should buy a little pot to feed and see if they are really enjoying the food. On the other hand, the fish food will grow old and stale with time from repeated exposure to moisture and oxygen, which could lead to health problems for your rainbow shark.


While most fish keepers will simply feed their rainbow sharks pellets or flakes that they were recommended at the pet store, some fish owners wonder if it is possible for a rainbow shark to eat veggies. The answer? Yes!

Fibrous veggies are great for rainbow sharks. You can add real veggies with their staple food a couple of times a week or so. I have used zucchini, cucumber, celery, and dark leafy lettuce. I weight them down with a rock and let them sink on their own.

Protip: Veggie clips are not recommended. These clips especially stacked a bunch of it together, can grab ahold of a fish leading to death.

If you’re looking for a safe way to feed veggies, I am in the same boat as you. I have heard of people blending the veggies up and freezing individual servings in the fridge, then using bag clips to hold the food and access to the fish. I think this method would work reliably, and I will definitely give it a try.

Hikari Algae Wafers

Photo: Hikari

An amazing vegetable matter fish food you might try, especially you noticed that the top or middle feeders in the community tank are capturing all the pellets. This original disc-shaped algae wafers product is specifically designed for hard-to-feed bottom dwellers. It’s rich in high levels of vegetable matter that your rainbow shark prefers, along with stabilized vitamin C to support immune health. What’s more, it sinks in water too fast and doesn’t pollute the water much.

Treats – Something Different & Nutritious

Just like us, variety is the spice of life. Nobody likes to eat the same thing every day. The same is true for the life of a rainbow shark. Feeding your sharks with a nutritious treat, such as daphnias, brine shrimp, or bloodworms per week can boost their brilliant colors and make them grow fast to full size. The best part? Your rainbow sharks love them!

Like feeding them vegetables, you might try pinching some below the waterline, making it sink right away.

How Often Should I Feed My Rainbow Shark?

As with most freshwater shark species, it’s better to feed your rainbow shark small amounts of food 2-3 times a day and more often, 5 days a week and skip two days or every other day, which will make him healthier and less susceptible to disease.

Don’t overfeed the treats, 1-2 times a week would be fine.


Can rainbow shark eat flakes in the tank?

Yes, if they are hungry enough, they’ll go after some flake for themself.

Do rainbow sharks eat algae?

Yes, they do eat algae while young then as it gets older, it moves to flakes and pellets.

Why my rainbow shark is a picky eater?

Some rainbow sharks get super picky about eating as they have gotten older. Try feeding your shark a different pet fish brand or frozen brine shrimp.

Why my rainbow shark doesn’t like treats?

Well, it’s rare, but some rainbow sharks are strictly vegetarian.

Why my rainbow shark is not eating?

  1. Try to feed your shark in tiny pieces.
  2. A variety will help things out, like bloodworm, tropical flakes, krill, brine shrimp, parboiled zucchini, and live crickets. 
  3. Is it a new shark? He could be picky a used fish food.  
Pro tip: If your rainbow shark refuses to eat, remember to keep an eye out for fish poop. Consider adding garlic extract (an excellent appetite booster) onto their regular diet in order encourage them back into eating habits!

Now it’s Your Turn

That’s all for now. I hope these tips prove useful to you! Anyone else has the best rainbow sharks food options and feeding tips, share with us in the comments below.

How Big Do Rainbow Sharks Get? (& How To Make Them Grow Faster!)

How Big Do Rainbow Sharks Get

If you need a single fish to make your aquarium stand out, the rainbow shark is just what you’ve been looking for. With their vibrant red fins and aggressive territorial nature, these little sharks will be sure to add some splash of color and spice up any tank with an attitude of their own!

If you’ve just brought home a beautifully colored rainbow shark or are considering getting one, there might be a question looming in your mind – how big do these sharks get eventually?

So without further delay, let’s get started!

How Big Do Rainbow Sharks Get?

Rainbow sharks are the sole shark, and they can grow up to 6 inches long. Although there are some differences between males vs. females, they tend to be about the same size in length. On the other hand, normal rainbow sharks and their albino varieties are all around about the same size when it comes to this measurement of length.

How Fast Do Rainbow Sharks Grow?

Rainbow Sharks grow pretty fast in the first year, then tapers off. My lovely red queen was 2″ when I bought her from the LFS 11 months ago and is now just over 5″. It seems to be growing at a slower rate. I have learned that it takes 2-4 years for a rainbow shark to get the full size by providing it with the proper care and diet.

How To Make Rainbow Shark Grow Fast

My lovely red queen
Photo: AquaMom

The best way to help your rainbow shark reach their maximum growth potential is simply by giving them the proper care and diet.


Diet is playing a most important part in your rainbow shark growth. As an omnivore, they are not particularly picky eaters in nature- generally eating decaying plants, algae, insect larvae or small chunks of meat that can be found in rivers such as Zooplankton.

Rainbow Sharks can eat flake food, frozen foods, pellets, and vegetables without complaint in an aquarium, but how do you make sure your shark gets all the nutrients he needs? To keep them happy in your aquarium, you need to offer various foods just like they would have access to if they were out in the wild. It’s not enough just feeding him canned corn-they need something more than vegetables from time to time too!

Feed them veggies in their diet, which will keep their immune system strong, include:

  • Zucchini
  • Cucumber
  • Dark Leafy Lettuce
  • Boiled Peas

Veggie chips are not recommended. It can grab ahold of a fish leading to death. I have tried to shred and blend the veggies up and then freeze them into individual servings in ice cube trays. It works for me! 

If you want to give your rainbow shark a brighter coloration, try to feed it a high-protein diet, such as good insects or crustaceans, include:

  • live bloodworms
  • artemias
  • Daphnias
  • brine shrimp

Make sure you don’t overfeed your rainbow shark, a few times a week would be fine. Feed them only what they can eat in a single meal and never try to make up for missed meals by feeding more food!

Juvenile Rainbow Sharks are a true treasure in the aquarium trade. They come with great colors and amazing shapes that make them one of the most sought after fish species. One thing to keep their colorful scales vibrant is never to restrict food intake, so it’s important to make sure your juvenile sharks’ diet be varied from time to time, or they will end up stunted and lacking color expression!

Tank Size

When starting as an aquarium hobbyist, you always want to find the perfect tank size for your fish. Have you heard the typical “one inch to one gallon rule” in the community? Honestly, I consider the rule is very bogus and misleading. Imagine a 6″ adult rainbow shark in a 6 gallon tank. That would be a disaster. 

The truth is rainbow sharks require a minimum of 55 gallons, and an aquarium of that size is suitable for one single rainbow shark. Don’t bother with the tanks smaller than 55 gallons, as mentioned above, rainbow shark grows fast in the first year and the aggression will come with age. Once reaching maturity(3 inches), it gets very aggressive overnight and started attacking the community fish. So stick to the recommended minimum tank size: 55 gallons. The long tank would be better. 

If you’re not experienced with rainbow sharks and planning on setting up a rainbow shark tank, you should keep a group of them or a single one, but never keep two rainbow sharks live together.  

For fish keepers who plan to introduce more than one rainbow shark, a 130g+ tank (at least a 6 foot long) can make sure each has at least a meter of separated territory. They will fight for control over their territories and inevitably injure themselves in the process.

Pro tip: I've found that sometimes my red queen becomes extremely aggressive and territorial. To calm her down, I move the decorations and plants around in the tank. It's kind of like giving her a new home (territory), which will 'reset' her behavior. You can try this, depending on what size tanks you have.

Tank Conditions and Care

The best way to take care of your rainbow shark is by providing it with an environment that mirrors the conditions in its natural habitat.

A healthy, thriving environment can affect how well your rainbow shark will grow. Before introducing a rainbow shark to a new tank, make sure the tank is fully cycled.  

The water temperature for your shark should be between 72 to 79℉, their prefer pH neutral waters between 6.5 and 7.5 and a water hardness of 5 to 11 DH.

Rainbow sharks are sensitive to pH level, sudden changes in the pH can make them more aggressive than usual.

Water quality is also crucial; be conscientious about algae growths, which will negatively affect fish habitats if left unchecked over time.

Protip: Rainbow sharks normally stay at the bottom, but they are renowned jumpers. So make sure you plug all excess holes and a hood is a must. The best way is put a cave to keeps its aggression in check. 

Final Thoughts

Rainbow shark growth depends on a variety of factors. Keeping your rainbow shark in a large tank, providing it with clean water and feeding it the proper diet will help grow to its full potential as quickly as possible. Good luck on growing your sharks into something even more amazing than before! 

Do you have any tips for getting your rainbow shark to get big? Share with us in the comments!

Rainbow Shark Tank Mates (5 Best & 5 Worst)

Rainbow Shark Tank Mates

Rainbow Sharks are fun and colorful fish to have at home, but there are several things to consider when keeping them with other fish.

Though not actual sharks, they get their name from the shark-like dorsal fin they have on top. Rainbow Sharks are originally Southeast Asian freshwater fish belonging to the Cyprinidae family and aren’t very aggressive in the wild. But they can be territorial while in captivity.

So, it’s essential to exercise caution before introducing tank mates for the Rainbow Shark. In this guide, we’re going to give you the complete low-down on the best Rainbow Shark tank mates.

Let’s dive in.

Can A Rainbow Shark Live Alone Without Tank Mates?

Behavior-wise, Rainbows can get somewhat territorial in close quarters, and this leads to them becoming aggressive. They are usually timid when young, but the aggressive side tends to become pronounced as they mature in proximity with other fish. 

In general, you’d need a larger tank (at least 75 gallons) to house a Rainbow Shark. Since they are territorial in nature, they don’t mind living alone without tank mates. If you’re thinking of introducing some mates, then make sure your tank has a lot of caves and hiding spots.

Rainbow Sharks are usually bottom dwellers, which means they can live in peace with top-dweller species. However, they don’t get along well with others of their kind and can exhibit hostile behavior such as biting, head-butting, and chasing.

Overall, we’d say a Rainbow Shark can live alone without mates very well. If you are thinking of introducing other fish in the same tank, make sure they are compatible with your Rainbow Shark. Otherwise, you’ll be facing severe trouble as it will attack other smaller fish.

How To Choose The Best Tank Mates For Rainbow Shark

Rainbow Sharks begin to show signs of aggression as they grow older. This is the time when you need to look out for them becoming hostile towards other fish in the tank. So, you’ll have to choose the tank mates rather carefully to ensure a peaceful aquarium environment.

Here’s a list of some of the considerations you need to keep in mind when selecting tank mates for Rainbows Sharks.

Fast Moving Fish

Fast-moving fish such as Harlequin Rasboras or Cherry Barbs are a good fit as tank mates for Rainbow Sharks. These fish can get away from Rainbow Shark territory faster and avoid any attacks coming their way. Faster fish can also compete well with Rainbow Sharks for food.

Don’t Have Long Fins.

When introducing mates into a Rainbow Shark tank, make sure they don’t have long fins. Since Rainbow Sharks themselves have a long dorsal fin, other fish with longer fins might obstruct their path, prompting violence from the Rainbow Shark.

Not The Same Or Similar Species

We recommend you don’t keep more than one Rainbow Shark in the same tank. These fish can be extremely aggressive towards the same species, or even other fish such as Red Tail Sharks, which look similar to them. We’ve observed Rainbow Sharks getting hostile with other freshwater shark species. 

The 5 Best Tank Mates For A Rainbow Shark In A 100g+ Long Tank

Here’s a list of the top five tank mates for a Rainbow Shark.

Cherry Barb

Cherry Barb

Cherry Barbs are an excellent choice as tank mates for Rainbow Sharks. These are peaceful freshwater fish that thrive in the tropical waters around Sri Lanka. They have an average lifespan of between 5 to 7 years and reach about 2 inches in length when they’ve fully grown.

These are active fish that live in schools, so you’ll have to introduce 4 or 5 of them in the tank. They are peaceful in nature, making them an ideal choice as tank mates for larger bottom feeders such as the Rainbow Shark. They are also fast swimmers, which is another reason they can survive in a tank with Rainbow Sharks.

Finally, the Barbs don’t like the bottom of the tank and prefer to stay towards the central region. This ensures that they won’t encroach upon the Rainbow Sharks’ territory in any way, causing it to feel threatened.

Scientific Name:Puntius titteya
Origin:Sri Lanka
Care Level:Easy
Color Form:Black, Red, White
Temperature:74-79° F
Minimum Tank Size:25 gallons

Harlequin Rasbora

Harlequin Rasbora

Harlequin Rasboras are another schooling fish that can be good tank mates for Rainbow Sharks. Rasboras are peaceful fish that live best in groups of 4 or 6; since they like to stay near the middle of the tank, it’s highly unlikely that a Rainbow Shark will see them as a threat.

Since Harlequin Rasboras grow to be at most around 2 inches, they are small enough not to bother the Rainbow Shark. At the same time, they can’t be easily gobbled up by it either. Further, the aquarium conditions preferred by Rasboras are also similar to those for Rainbow Sharks.

Scientific Name:Rasbora heteromorpha
Care Level:Easy
Color Form:Orange
Temperature:72-77° F
Minimum Tank Size:10 gallons

Clown Loach

Clown Loach
Photo: lews_tank

Clown Loaches are middle to bottom dwellers, so theoretically, you shouldn’t put them in the same tank as a Rainbow Shark. However, we’ve observed that Rainbow Sharks do get along well with Clown Loaches, maybe because they live in close proximity in the wild.

The trick to getting Clown Loaches to live peacefully with Rainbow Sharks is to provide a lot of hiding spots for both species. Also, Clown Loaches fall in the optimal size range, so they’re neither too big to obstruct, nor can they be easily eaten by a Rainbow Shark. 

However, a word of advice: different Rainbow Sharks have different temperaments, and some might not get along well with Clown Loaches and feel threatened. In that case, you’d need to move them to separate tanks immediately.

Scientific Name:Chromobotia macracantha
Care Level:Moderate
Color Form:Black, Orange, Red, Tan
Temperature:72-86° F
Minimum Tank Size:100 gallons

Zebra Danio

Zebra Danio
Photo: bob_jenkins

Zebra Danios are beautiful fish that have stripes similar to the animal they are named after. Also called Striped Danios or Zebrafish, they are usually found in South Asian waters. And since they are typically found at the top or middle of the tank, they are perfect as tank mates for a Rainbow Shark.

Small and naturally peaceful, Zebra Danios live in shoals. Also, they are relatively fast swimmers, which means they can get away from the Rainbow Shark before it can attack them. 

What’s more, their tank requirements and food habits are similar to Rainbow Sharks. And they grow to almost 3 inches, which is large enough for the Rainbow Shark to give them a miss as food.

Scientific Name:Danio rerio
Origin:Farm Raised – USA
Care Level:Easy
Color Form:Blue, Purple, White, Yellow
Temperature:64-75° F
Minimum Tank Size:10 gallons

Bristlenose Pleco

Bristlenose Pleco

The primary reason a Bristlenose Pleco makes for good tank mates with Rainbow Sharks is their larger size. This means, although they are usually bottom dwellers, the Rainbow Shark is unlikely to pick a fight with it due to its massive size of almost 2 feet.

Further, Plecos are an extremely tranquil variety of fish and aren’t likely to fight with your Rainbow Shark. Keep in mind that these choices will only work well if you have a wide enough tank of at least 100 gallons.

Scientific Name:Ancistrus sp
Origin:South America
Care Level:Easy
Color Form:Orange, Tan, White
Temperature:74-79° F
Minimum Tank Size:30 gallons

The 5 Worst Rainbow Shark Tank Mates To Avoid



Guppies are one of the most popular aquarium fish species and are great for beginner aquarists. They are very hardy fish and can be prolific breeders when provided with the right conditions.

However, they make for one of the worst tank mates for Rainbow Sharks. Rainbow Sharks are larger than Guppies and also much more aggressive. As a result, they can bully the Guppies if they’re put in the same tank.

Further, Guppies are livebearers, which means that the fry are already swimming freely at birth. This can become a severe problem as the Rainbow Sharks will most likely end up eating the fry.



Gouramis are slow-moving tropical freshwater fish that are found in the South Asian waters. They are an egg-laying species and are air breathers. So, you can usually find them towards the top of the tank.

Despite being top dwellers, Gouramis are not suitable fish for keeping with Rainbow Sharks for several reasons. For one, Gouramis (especially males) tend to be aggressive and territorial and can get into fights with the Rainbow Sharks.

Several species of Gouramis, such as the Giant Gourami, can get very large and may be unsuitable for keeping with Rainbow Sharks. Again, other Gourami species are too small to be kept with Rainbow Sharks as they might get eaten.

Also, since Gouramis are slow swimmers by nature, they won’t be able to compete with the Rainbow Sharks for food. 


Corys are usually great for freshwater community tanks, but you can’t keep them with a Rainbow Shark. Corys are a calm and peaceful species and can’t compete with the semi-aggressive Rainbow Sharks. 

Another reason for not keeping Corys and Rainbow Sharks together is that Corys are also bottom dwellers. This means the Rainbow Shark(s) will see them as encroachers on their territory and are most likely to attack.

African Cichlids

The African Cichlid comes in several species, each with its own distinct coloration and patterns. These are aggressive fish that grow up to 8 inches in size and can live up to 15 years, depending on the species and living conditions.

Since African Cichlids are similar in size and aggression to Rainbow Sharks, there’s a good chance that they will get into fights with each other. Further, as they are bottom dwellers and territorial, African Cichlids don’t go well with Rainbow Sharks.

Yet another reason for not keeping Rainbow Sharks with African Cichlids is the water condition. While Rainbow Sharks prefer a pH level of 6.5 to 7.5, Cichlids prefer pH levels of 7.5 and above. 

There’s also a temperature difference; Rainbow Sharks prefer waters between 72 and 82 degrees Fahrenheit. African Cichlids like warmer temperatures in the range of 75 to 85 degrees Fahrenheit. As a result, you might find it difficult to hit upon the ideal water parameters when keeping these fish together. Read more

Most Of Freshwater Sharks

In general, we recommend you keep only one Rainbow Shark in a tank at a time. Rainbow Sharks don’t take well to other freshwater sharks that look and behave similarly to them. We’ve even seen them become aggressive towards Albino Sharks.

Since Rainbow Sharks live a solitary and territorial life in the wild, the same behavior is reflected in captivity. As a result, they can’t tolerate other Freshwater Sharks such as the Red Tail Shark or even Bala Sharks. 

If you’re keeping any of these fish with a Rainbow Shark, be very careful and look out for bite marks or nipped fins. They can get extremely aggressive with each other.

Tips To Introduce Rainbow Shark Tank Mates

Introducing tank mates for Rainbow Sharks can be tricky, especially if your tank size is limited. Rainbow Sharks can be unpredictable, and temperaments vary from fish to fish. Still, here are a few general tips to keep in mind when introducing Rainbow Shark tank mates:

  • Always choose tank mates that are middle or surface dwellers
  • Never keep other freshwater shark species with Rainbow Sharks, especially the same species
  • Select fast-moving fish as tank mates that can quickly get away from the Rainbow Shark
  • Make sure the species have similar water parameter requirements
  • Be certain that the species is large enough so that the Rainbow Shark can’t eat them


Can rainbow sharks live with tetras?

Rainbow sharks can live with tetras in a big community tank, especially these tougher types of tetras, such as Serpae tetras, black skirt tetras, etc. DThe weaker tetras including rummy nose, neons and cardinals can easily be eaten by just about anything.

Will a rainbow shark eat other fish?

The rainbow shark is an semi-aggressive species that will pick a territory. such as a cave or anywhere it can hide and defend them from intruders. They are extremely savage with conspecifics and similar shaped fish like other sharks and and algae eaters.

Can 2 rainbow sharks live together?

No, never keep just two rainbow sharks in the same tank. Rainbow sharks can get aggressive with conspecifics. Either keep a group of them (5 or more) from fry or one rainbow shark in a single tank.


We hope you now have a better idea of the requirements you need to keep in mind when introducing tank mates for Rainbow Sharks.

As we’ve already mentioned once above, choosing tank mates for Rainbow Sharks can be rather a tricky task. They are temperamental fish that are known to bully other tank mates. In extreme cases, they can even go in for direct attacks.

However, if you can keep the suggestions and recommendations mentioned in this guide, we’re sure you’ll be able to find suitable mates for a Rainbow Shark. Just keep a close watch on the community for a while, and observe how the Rainbow Shark reacts.

Till then, enjoy your aquarium!

7 Most Popular Types Of Danios (+ With Pictures)

7 Most Popular Types Of Danios

Lively and tiny – Danios will be the most pleasant and playful companions in your aquarium. 

These hardy fishes survive in unheated tanks and have minimal maintenance requirements, making them the top pick for novices and experienced aquarists. Besides, they are small-sized and do not require large aquariums to move around. 

So, if you are looking for tiny fishes for your small aquarium space, there’s no need to look any further. 

In this guide, we will look at the different types of Danios and tell you everything you need to know about them. So, without further ado, let’s begin. 

Danio Fish Types

Although there are different types of Danios, only a handful of species are commonly available. We’ve listed them here for you. Let’s take a look.

Zebra Danio

Zebra Danio
Photo: fro_Ost

Zebra Danios are a popular pick for freshwater tanks with their gorgeous stripes and small size due to their unfussy nature and minimal requirements. These South Asian natives are omnivores that can grow up to 2 inches and require a tank capacity of 10 gallons.

They have a spindle-shaped body, with five iridescent stripes running along its length, and prefer to live in groups. So, always keep at least five or more Zebrafish in your tank.

Active and playful, these fishes are non-aggressive and can live with other species of the same size. The ideal water temperatures for them are around 64 to 77℉.

Celestial Pearl Danios

Celestial Pearl Danios
Photo: CheepShot

Originating from South East Asia, Pearl Danios have white-spotted bodies with red or orange fins and lighten up any aquarium they are placed in. These fishes are no bigger than two inches and are quite shy and mellow. So, always keep them in groups with similar-sized species, or else they might fall prey to large fishes.

Moving on, they prefer heavily-vegetated tanks since it resembles their natural habitat and gives them more space to hide while laying eggs. The males of the species tend to get aggressive while looking for mates, so always keep more female fishes in the tank.

White Cloud Mountain Minnows

White Cloud Mountain Minnows
Photo: moontan

White Cloud Mountain Minnows are brightly colored fishes originating from China. They are hardy and can survive different water conditions and temperatures. Ideally, they should be placed in water temperatures of 64 to 72℉ but can stay in unheated tanks, even if the temperature falls as low as 41℉.

Always keep them in schools of 6 or more (in a balanced male to female ratio), and they breed easily, spawning several times a year. The male species tend to get aggressive during the mating season, so it might be better to shift them in separate 7-gallon tanks.

In addition, these fishes grow no bigger than an inch or two and are easygoing when kept in groups, making them excellent tank mates for a large variety of similar-sized species.

Giant Danios

Giant Danios
Photo: Jubs13

Another fish from the Minnow family, Giant Danios, are freshwater fishes that can grow up to 4 to 6 inches, making them one of the largest Danio species.

Although they are generally peaceful, you should keep them with species similar to their size, or else they can prey on smaller fish varieties. Their large size makes them compatible with Cichlid tanks, as long as they are kept in groups.

These fishes are quite active and playful, and therefore need ample space to move around. Ideally, their tank should be no less than 30 gallons. Also, Giant Danios jump a lot, so don’t forget to cover your tank.

Glowlight Danios

Glowlight Danios
Photo: swordw

Another shoaling species they are bright-colored and peaceful, preferring cooler water temperatures and dense plant cover. These grow a little over one inch and are pretty active, requiring a minimum tank capacity of 10 gallons.

Since these fishes are shy, ensure there is sufficient hiding space for them to breed. Usually, a combination of coarse gravel and aquatic plants will suffice.

Spotted Danio

Photo: Choy Heng-Wah

Originating from Myanmar, Spotted Danios are freshwater fishes that are less than two inches long. As their name suggests, they are characterized by the appearance of iridescent spots that run along with their silver-colored bodies.

They are timid fishes that do well if kept with creatures their size. Suitable tankmates include Cory Catfish, Glowlight Danios, and Small Tetras. Ideally, they should be kept in a large school of 6 or more fishes.

Rose Danio

Photo: wikipedia

Rose Danios make great tank mates, as long as the fishes are of similar sizes and peaceful. They are hardy and easy to care for, growing around 2 inches and constantly moving around.

An important point you should remember with this species is that they require soft water, with temperatures that range between 68 to 77℉. Ideally, a group of twenty or more fishes will thrive in a community tank, but you can also keep 6 or 7 Danios in a 20-gallon tank.

Frequently Asked Questions

How Many Danios Should Be Kept Together?

Since Danios thrive well in groups, you should keep a minimum of 6 fishes in a tank of 25 gallons.

What Types Of Danios Are Best For A 10-Gallon Tank?

If you have a smaller aquarium, then you should choose Celestial Pearl Danios and Zebra Danios. They are small in size, non-aggressive, and can survive in small tanks.

Can Different Types Of Danio Breed?

Danios can be genetically modified to breed. Besides, some species like Zebra Danios breed with their subspecies (Leopard Danios). Crossbreeding is usually discouraged since it leads to infertility and reduces the lifespan of Danios.

Can You Mix Different Types Of Danios?

Although different Danios of similar sizes can live together peacefully, they can tell their species apart and tend to become reclusive instead of schooling. 


That’s all for today!

We hope you can now select the right species of Danios for your aquarium. Remember, Danios are peaceful, active, and hardy – so as long as you fulfill all their requirements, these fishes will add a stunning charm to your space without being troublesome. 

A word of advice before we go: clean the water tanks frequently since the buildup of toxins is detrimental to the health of Danios. Until next time, take care!

Pregnant Goldfish Care: How to Tell If a Goldfish is Pregnant

Pregnant Goldfish Care

Is your goldfish pregnant? Can you expect them to lay some eggs in the not-too-distant future?


While noticeable weight gain on a goldfish is one of the biggest signs a goldfish is pregnant (more on that later), it isn’t a guarantee. There are in fact several potential indicators that your goldfish is expecting.

We’re going to cover the biggest tell-tale symptoms of a pregnant goldfish. We can also cover some basic care tips to help you. These tips can be helpful for both those who are not anticipating a pregnant goldfish, as well as those who are actively trying to breed them.

How to Tell If a Goldfish is Pregnant?

First of all, it is important to make a distinction here: While we are using the term pregnant goldfish to describe goldfish who are potentially about to lay some eggs, they are not actually pregnant in the technical sense. This is because the animals that can actually get pregnant are those which partake in live births.

Goldfish don’t. However, they can become full of unfertilized eggs. What happens after that can depend on a variety of different factors. It starts with knowing exactly what to look for in goldfish that are on the verge of breeding.

At the end of the day, that chubbiness could simply be due to the fact that your goldfish is overweight!

Symptom #1: The Belly

Let’s get the stomach out of the way once and for all.

A goldfish is pregnant will indeed look chubby, particularly around the belly. Keep in mind that this is not the same thing as being swollen in appearance. That could prove to be something else altogether.

There will be a slight-but-noticeable plumpness to them. While not a guarantee that the goldfish is about to lay some eggs, it is definitely the first significant sign you’re going to want to look for.

Also: As we mentioned before, it could be possible that you are overfeeding them, or that they are eating too much. Monitor your goldfish, and double check the directions for whatever you’re including in their diet. Don’t feel too bad. A lot of people overfeed their goldfish!

Symptom #2: Being Chased

During the breeding period, which can occur as early as in the first year, the female is going to become heavy with eggs. She will be looking for a place in which to lay them. We’ll discuss one of the biggest indicators of eggs you’re going to have, but for now, let’s focus on what the males in your tank are doing.

Male goldfish can be a real nuisance sometimes. When they sense that the female is filled with eggs, they’re going to look for a place to put their fertilization efforts to work. This biological need can be witnessed by simply observing the male and female interacting with each other.

When the female is ready to dump those eggs, they release a unique pheromone. This sends the definitive signal to the male, eager to fertilize. They will be excited to do this, seemingly, they will start chasing the female around the aquarium. They may even slap at the female with their fins.

While normal behavior, occurring during the spring and summer seasons, you should still keep an eye on it. If the male bothers the female for a significant amount of time, it can wreak havoc on their health. You may need to eventually move the female to a separate tank for a couple of days.

Symptom #3: Dropping Eggs

This is obviously one of the clearest examples of a goldfish about to lay eggs. It may be a little strange to imagine eggs literally spilling out of the goldfish, but this is indeed something that can happen sometimes.

If you really want to know for sure if the female has eggs, you can pick them up, and let them wriggle gently inside your hand. If they are in the best possible breeding shape possible, eggs may start falling out of them. This is even something breeders sometimes do, if the situation warrants such a move.

That is a big “if.” Squeezing your goldfish can also cause health issues and serious stress.

Pregnant Goldfish

How to Take Care of A Pregnant Goldfish?

One common myth we should do away with: Does it mean my goldfish is pregnant if they’re spending increasing amounts of time on the bottom of the aquarium?

No. In fact, if your goldfish is doing this with greater frequency, the odds are unfortunately quite high that they are sick. This is also true of a belly that appears swollen, as opposed to simply chubby.

Pay attention to appetite, as well. The goldfish is still going to have a healthy appetite. If your goldfish is not eating, it could be a sign that they are sick.

In terms of taking care of your goldfish, there are a number of things you can do. Check out this guide on breeding goldfish to see what you need to do, if you are planning to purse the avenue of breeding them for fun or profit. 

Remember that females may decide to eat their eggs after laying them. If you plan to breed goldfish, this is one of the most important considerations you are going to want to keep in mind.

If you don’t want baby goldfish, then make it a point to separate the male from the female for a couple of days. You can also simply see if nature will take its course.

Do Guppies Have Menopause? (An Interesting Answer)

Do guppies have menopause

When we think about guppies, menopause probably isn’t one of our initial thoughts. However, as a recent study indicated, female guppies do indeed experience menopause. This means there is more to their life than simply breeding and having babies. In general, as we have learned through studies just like the one mentioned, there is more to guppies than many people realize.

From the fact that female guppies experience menopause exactly as human females do, many compelling questions are beginning to emerge.

For example, why are some female animals continuing on past their optimal fertility years?

What Exactly Is Menopause?

Before we get deeper into the female guppy and menopause, let’s go over a brief definition of menopause.

Menopause refers to the natural leveling out of reproductive hormones in many female animals. This leveling out eventually gives way to decline. In the United States alone, more than 2 million new cases are diagnosed every year. Vaginal dryness, mood swings, and hot flashes are the most common symptoms. Various treatment options can be utilized, and most females who experience menopause do so without significant change to their lives. This thought extends to guppies. For any species, menopause marks the end of one’s reproductive years.

Symptoms generally lessen and/or disappear after four or five years.

What Does All Of This Mean For Guppies?

Guppies have always been grouped as animals whose purpose is fulfilled, once they have successfully extended their species. However, with this recent study showing us that the females go through menopause, this grouping no longer applies. Menstruation is a process which, among other things, tells us an animal, including humans, does not exist solely to breed.

Evolutionary theories aside, it is clear that female guppies have a role to play in their ecosystem, beyond the value of reproduction. This role can be potentially realized in several ways.

What Roles Do Guppies Fill Beyond Menopause?

This is where things can get interesting. If we believe that virtually everything in nature has a purpose, at any given stage of its lifespan, then it’s tempting to assume female guppies continue to be useful after their prime years of reproduction.

The notion of older female guppies acting as protectors for younger guppies is one theory that has been put forward. Many believe they have witnessed this behavior in action. Simply put, the older females are bigger, more easily visible, and are generally faster than their more youthful counterparts. All of these traits could be beneficial in the ecosystem of the guppy.

Keep in mind that this is just one possibility of many. Some believe female guppies simply exist after their reproductive years have passed, regardless of whether or not they have anything to contribute to the ecosystem.

This is something that will certainly require more study. Remember, this study was only released just fifteen years ago. That may sound like a lot of time, but studies such as these often demand a good deal of patience. Furthermore, there remains a sizable portion of individuals who are completely unaware that menopause occurs within female guppies.

What Happens To Female Guppies When They Enter Menopause?

If you do some research on guppies beyond this article, you will find a number of interesting anecdotes and facts about how they age. Particularly with the females, it has been said that you can always tell when they become menopausal. This, they say, is due to the older female guppy becoming fatter over time.

That is not altogether accurate. Yes, female guppies during menopause become bigger, but that doesn’t necessarily translate to becoming fatter. Many seem to become longer, as opposed to fatter. However, a certain amount of weight gain can still occur. It just doesn’t seem to be focused on the belly.

On average, guppies reproduce at a pace of roughly one litter every thirty days. This translates to approximately twenty litters of anywhere between thirty and fifty baby guppies. Beyond the astonishing fact that female guppies can have as many as one thousand babies in their lifespan, there does seem to a point in which this pace dramatically slows down. Older female guppies produce less as they approach menopause, compared to when they were younger. By a certain age, they seem to stop having babies altogether.

Yet they continue on.

A Few More Fascinating Facts About Guppies And Menopause

The 2005 study we cited at the top of this article has a few more fascinating elements to ponder.

A study conducted prior to the 2005 study showed the following: Guppies from areas with comparatively more predators than other guppies not only lived for a longer period time, but they also tend to start reproducing at a younger age, compared to guppies that lived in less risky areas. It was the mission of the 2005 study to figure out why this was occurring in the first place.

By the time the 2005 study had been completed, researchers were able to make a number of interesting predictions:

  • Female guppies do NOT provide maternal care to their babies, once they have given birth. The theory remains that female guppies can provide protection to younger guppies from predators, but this not a fully established proven concept, as we mentioned earlier.
  • “Fitness” is the term used by scientists to describe the ability of an animal to reproduce. From this specific perspective, researchers are still not clear on why female guppies continue to live after their reproductive years have concluded.

There is a theory that this is simply because the female guppy breaks down in different stages.

Conclusion: What We Definitively Know About Female Guppies And Menopause

By the way, the notion of older female guppies providing protection to younger females is known as the “grandmother effect.” The only species in which this behavior has been definitively found is in humans.

What we know for certain is that because female guppies continue to live full lives after their breeding years, their lives are not defined by natural selection. In other words, a guppy does not need to specific and constant biological function to justify its existence.

Pretty thought-provoking stuff!