Red Spots On Goldfish: Symptoms, Causes & Treatments

Red Spots On Goldfish

(As an Amazon Associate we earn from qualifying purchases. The Aquarium Fish City is reader-supported and we hope you love the products we recommend!)

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? 

Goldfish are more sensitive to changes in their environment than humans, so it’s no surprise that many factors can cause red spots on the fins, tail, and body.

The Most Common Reason: Red Pest Disease

As the name suggests, red pest disease is a condition that affects goldfish and other pets, causing them to develop red, bloody streaks on their tail, bodies, fins, and sides. 

However, this condition does not necessarily have to develop specifically in these areas. It is not uncommon to find red spots or streaks on other body parts, so make sure you look carefully to see the signs. 

The primary reason for red spots to occur on your goldfish’s body is due to poor water conditions. This causes the infestation and growth of bacteria on the fish’s bodies. However, rest assured that this condition is not contagious, so it isn’t possible for one fish to transmit it to another.

Furthermore, this condition typically appears on weaker fish, so the ones with stronger immunity may not face it. 

What Is Red Pest Disease In goldfish?

Red Spots On Goldfish picture
Photo: sunshine320159

Red pest disease, also known as pond pest, is a condition that causes red, bloody streaks to develop on the side, head, and body of a goldfish. It is typically an internal disease, and more often than not, external medications do not cure it. 

However, if a pet owner is able to catch the disease in its early stages, they may be able to reduce its spread with the help of antibiotics. Since the disease is caused by a bacterial infection, it is essential to treat the tank water first, ensuring that it doesn’t spread amongst the other fish. 

Goldfish Red Pest Disease Causes

There is only one primary reason for red pest disease in goldfish – poor tank water conditions. You need to ensure that your aquarium is cleaned and maintained regularly, without which, the water condition can deteriorate. 

This causes bacterial infections to spread through the tank, affecting weaker fish and forcing them to succumb to red pest disease. A fungus known as Aphanomyces invadans begins growing in the dirty water, slowly spreading to the goldfish’s scales, gills, belly, nose, and eyes (in severe, untreated cases.)

How To Treat Red Spots On goldfish?

red pest disease goldfish

Now that you know the leading causes and symptoms of red spots on goldfish, you may be wondering how to treat it. Keep in mind that since red pest disease is an internal disease, you need to treat the tank water first, then give internal medication like antibiotics to your goldfish. 

Before treating the tank, ensure that you move your goldfish to another area where they can rest. Then, add five teaspoons (per gallon) of medicated, fish-friendly, non-iodized aquarium salt to the tank. 

You can add a disinfectant such as Acriflavine (Trypaflavine) to the tank, which will treat the bacteria in it. You can also choose to add Monacrin (Mono aminoacridine) in case Acriflavine is unavailable. 

Next, you should add Methylene Blue or Malachite Green to the tank. The former option is much safer for your fish than the latter. 

Recommended Antibiotics For Treatment

The next step is to feed antibiotics to your goldfish. Before doing so, ensure that you don’t feed your fish for a while so that they are hungry and will eat their antibiotics and medicated fish food. Tetracycline and Chloromycetin (Chloramphenicol) are two safe options you can consider. 

Do not add more than 10mg of medication per liter of water unless it is a severe case. 

External Medications

As we’ve already mentioned in an earlier section, the first thing you need to do is clean and disinfect the tank using a fish-friendly disinfectant like Acriflavine (Trypaflavine) or Monacrin (Mono aminoacridine). You should also add non-iodized aquarium salt to treat the water. 

Ensure that you regularly clean the tank and add Methylene Blue to it. Moreover, purchase a water testing kit to know how much and when you need to clean the tank. 


Is Red Pest Disease Contagious In goldfish?

Fortunately, red pest disease is not contagious, so you don’t need to worry about it spreading from one infected fish to another. However, keep in mind that this disease primarily attacks weaker goldfish with low immunities. 

As the water conditions in your tank begin deteriorating with the spread of bacteria, it is likely that other goldfish in the tank will also be affected by the disease. So, it’s vital to keep an eye on your goldfish and notice the symptoms of red pest disease – before it is too late. 

That said, this disease is relatively easy to treat. If you are able to catch it in its early stages, simply cleaning the tank with disinfectant and external medications can help you treat the disease. Of course, it is best to add antibiotics to your goldfish’s food and feed them live food to help treat and cure the infection in a better way. 

Also, regularly clean and maintain your aquarium to prevent the disease from recurring or spreading. 

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. 

Recommended Reads :

Jeff Colt

Jeff Colt

Hello, I'm Jeff- an aquarium enthusiast with over ten years of experience caring for a wide array of tropical fish, including koi, goldfish bettas, cichlids and more! For me: Aquariums are like jello - there's always room for more!

Leave a Comment