20 Most Popular Freshwater Fish for Your Aquarium

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The fact that freshwater fish are the number one pet in America should come as no surprise. An aquarium, especially for freshwater fish, is fairly easy to maintain and they have become a staple of the American home.

Besides being gorgeous to look at, you will find that each freshwater aquarium fish displays unique behaviors and character traits that makes keeping them a true joy.

Because there is such a wide variety of freshwater fish waiting to fill your aquarium, let’s explore some of the options that are out there, and hopefully one of these beautiful fish will be the one for your tank.


This highly adaptable freshwater fish offers a wide variety with over 1270 unique species of killifish. Mostly common in the Americas, killifish reside in freshwater or brackish lakes, streams and rivers.

A killifish can be expected to live between 2 and 3 years, but they are highly resilient. This fish would include the mummichog or pupfish. Most killifish will range between 1 and 2 inches, but some of the bigger species can reach up to 6 inches.

Killifish are known to make good pets and have been popular aquarium fish for years because of their appearance and lifespan. The Golden Wonder killifish is the most commonly sold one in pet stores across America, but caution is encouraged if it is cohabiting your aquarium with other fish as they have large mouths more than big enough to swallow their roommates.


Guppies have long been a staple of aquariums across the world. Besides being distinct looking and easy to care for, guppies have unique personalities and are amazing to observe.

These fish range between 0.6-2.4 inches long and usually are covered in colored spots, stripes and patterns that have made them well known. Their diet is simple and you can feed them everything from mosquito larvae to brine shrimp, but it’s important to mix it up to give them variation in sustenance.

Because of their size, guppies will be able to do well in anything above a 5 gallon tank, but I would personally recommend going with a 10 gallon tank, especially if your guppies are sharing a habitat with other fish.



Goldfish are one of the most iconic freshwater aquarium fish for a reason. Rather small for a member of the carp family using coming in at around 4 inches, goldfish are easy on the eyes and leave room for other inhabitants in your aquarium.

Beyond pellets of “goldfish food”, goldfish can be fed anything from boiled vegetables and crustaceans. They are known to be friendly fish and have a reputation of playing well with others.  Goldfish also have earned the reputation as being low maintenance, even going up to 8-14 days without food and still living. This is not recommended, however, as you want to give your goldfish the best and healthiest life possible.

Depending on how many goldfish you are looking to get, it’s important to remember that goldfish do best when they are given 6-8 gallons of freshwater each. If you are looking to get several goldfish, check to make sure your tank can accommodate them.



The Siamese fighting fish, more commonly known as bettas, are a stunning addition to any aquarium. Despite their elegant and beautiful appearance, they earned their “fighting fish” nickname due to their territorial tendencies.

Thriving best in water temperature of 75-82 degrees Fahrenheit, you are going to want to use a heater if you are in a cold climate or your tank is in a cold spot. Bettas are highly resilient and a single one can survive in merely 1 gallon of water, however, if you are planning on having multiple bettas or want a betta to join your other fish, you will want to use a bigger tank.

Bettas have an average lifespan of 3-5 years. It’s important to remember that bettas are competitive, territorial and if you are mixing them in with your other fish, keep a close eye on how they interact with the one another.


André Jaconi (Source)

A member of the cichlid family, the oscar fish is a species full of variety that has thrived in freshwater aquariums for years as a popular pet store fish.

Having the potential to grow up to 18 inches, oscar fish require a strong diet in order to stay healthy. You will want to feed an oscar fish food that is intended for carnivorous fish, such as crayfish, insects and worms.

Oscar fish are particularly sensitive to cold water, with temperatures of even 55 degrees Fahrenheit being enough to kill them. It is recommended that you keep their water at 77 degrees Fahrenheit and provide them 30 gallons of water as they are quite large.

Oscar fish are known to play dead by laying on their side, so don’t be alarmed if you see them turned over.

Neon Tetra

Neon Tetra​

Small, versatile and low maintenance, the neon tetra is a gorgeous aquarium fish. Not usually growing larger than 1.2 inches, they won’t take up much space in your aquarium.

Their diet is simple as they are omnivores and can handle anything from freeze dried vegetables to worms and insects. They are quite popular as aquarium fish because of their bright colors and they tend to do well with other fish.

With proper care and under the right circumstances, a neon tetra can live up to 10 years. You will need to provide 10 gallons of water per 24 neon tetra. Neon tetras tend to do their best in a tank that is densely populated and full of plant life.

There is however a condition uinuqe to tetras, called “neon tetra disease” in which they eat infected material, such as a dead fish, causing parasitic spores to weaken them. This is avoidable by regular tank cleaning.

Cherry Barb

The cherry barb is a small, tropical freshwater fish. Female cherry barbs tend to take on greenish tones with a stripe while males have a red color to them. In the wild, they are found in shallow and shaded habitats and mimicking this in your tank will make them feel at home.

Because cherry barbs are schooling fish, it’s important that you keep them in a group of 5 or more. It’s important to get the proper ratio, with 2 females per 1 male, to keep balance and prevent territorial behavior.

Usually, a cherry barb won’t exceed lengths of over two inches. In general, you are going to want to give 5 gallons of water per cherry barb, and because they are schooling fish, you are going to want at least 25-30 gallons of water for them.



Koi fish are an icon amongst fish hobbyists kept in water gardens and koi ponds. Although koi are cold-water fish,  they are known to thrive in temperatures between 55 and 77 degrees Fahrenheit.

A koi pond is typically going to be 5 feet deep, with the rule of thumb being that you give 10 gallons of water per one inch of fish. Koi also have an easy diet being able to handle everything from peas and lettuce to even watermelon.

You can find koi that are white, black, orange or yellow amongst an even wider variety of colors. Koi have the potential to reach 3.28 feet in length or even larger, so you will want to choose a habitat that can accommodate growth. Koi also have an incredible life span with healthy ones being able to live between 25 and 30 years.

Freshwater Angel Fish

Freshwater Angel Fish
Paulius Vengialis (Source)

Freshwater angel fish have been distinct fixtures in aquariums for years. Their angelic fins, stripes and color patterns make them stand out in a habitat while camouflaging them in the wild.

Growing up to 6 inches long, freshwater angel fish are a good mid-sized aquarium fish. They do best in pairs at the least and require 20 gallons for two of them. If you are looking to get a school of 5 or more of them, which is advised, you will need at least 80 gallons.

Freshwater angel fish do best in water temperatures of 80 degrees Fahrenheit. They are known to be peaceful fish, but may pose a threat to smaller fish. They do very well when stuck together with other angel fish species but should fit in with most common aquarium fish.



The silvery scales of the small molly fish give it a memorable sheen in any tank. Most mollies that you’ll find will range between 3.2 and 4.8 inches in length, with only females usually reaching the latter.

Because there are seven varieties of mollies, they offer a wide range of options and spectrum of color that you can bring to your aquarium. While female mollies are perceived as being peaceful fish, male mollies are known to sometimes display aggressive behavior.

Molly fish also make for a good choice if you’d like to get fish that will last you a long while with proper care. They can live up to 5 years given the proper nourishment, and in an aquarium flake food and vegetables is perfect for them.

Discus Fish

Why Are Discus Fish So Expensive
Roby Bonnes (source)

Hailing from the Amazon, the discus fish is best known for its namesake shape. Truly unique patterns don their disc shaped bodies and their social nature makes them a joy to observe.

Discus fish are well known as being social fish often traveling in groups which is not common of cichlids. They do well in aquariums with one or two other discus fish.

Discus fish usually reach between 4.8 and 6 inches in length and require a meaty diet. They can do well with flakes, but you are going to want to ad variety to their diet by giving them anything from mosquito larvae to earthworms.

They thrive in larger amounts of water due to their size, needing up to 100 gallons if you plan on keeping several discus fish at once.

Jack Dempsey Fish

Named after the famed boxer of the same name, the Jack Dempsey fish gets its name for its aggressive tendencies.  Native to South America, Jack Dempsey fish are instantly recognizable from their colors often combining blue and purple hues with green and gold specks.

Despite their reputation for being aggressive, Jack Dempsey fish are quite popular aquarium fish. They tend to do well with larger fish populations provided the habitat suits them. Jack Dempsey fish do best when they are provided places to hide. You can expect for them to live up to 8 to 10 years.

They do well with a variety of food but you will want to throw in meatier options from time to time. You’ll want to keep the water between 72-86 degrees Fahrenheit.

Cory Catfish

Cory Catfish

Cory catfish have long been an ornamental fish in the world of fish hobbyists. They are extremely benign and calm, spending much of their time scaling the bottom of the tank and feeding off of descending flakes.

Most cory catfish in captivity will have an average life span of 5 years, but there have been several instances of them living beyond 20 years in captivity due to their active and simple lifestyle. They are very small, rarely growing past 2.5 inches long.

Cory catfish are schooling fish, so you will want to get at least 6 of them. Not only will it make them happier, but it is also amazing to observe. They are quite low maintenance and are easily sustained by flake food.

Electric Blue Acara

Vividly colorful, the electric blue acara fish is another freshwater cichlid that is often sought out for its appearance.

Usually maxing out at around 6.3 inches, the blue acara is a stocky bodied fish with thin, flowing fins. You will be able to recognize 5 to 8 colored stripes on most blue acara as well as their trademark black stripe going from their eye down their face.

Electric blue acaras are a good investment when bought young as they can live up to 10 years in captivity. Because they are omnivorous, you can also feed them a variety of foods. Giving them a balance of meatier foods, flakes and dried vegetables will best replicate their diet in the wild.

They are very peaceful so long as they are not paired with aggressive fish.

Zebra Danios

Zebra Danios

Commonly referred to as zebrafish, the zebra danio is a member of the minnow family. Because of that, they are just as small as you may expect.

It is rare for a zebra danio to grow larger than 1.5 inches, but healthy zebrafish in captivity have been observed to reach 2 inches. Zebrafish reach their peak as school fish. Because they are cheap, getting a school of 6 or more zebra danios won’t set you back too much and will maximize their quality of life.

You will find that they will live up to 3.5 years old, but in that lifetime, they will be quite active. One of the many appeals of zebra danios is the visual spectacle they put on. They are known for being particularly playful with one another and getting along with other fish.

Red Tail Shark

The red tail shark is not in fact a shark at all. In fact, they are not even related to sharks at all, but their distinct shape definitely evokes imagery of sharks.

The red tail shark, also referred to as red-tailed black shark, is actually a member of the carp family. Reaching up to 6 inches, these carp essentially look like small carp with a similar body shape to that of a shark.

Their bodies are black with the only color coming from their namesake red tails. As the name may suggest, red tail sharks are known for being semi aggressive in the aquarium setting. In the wild they are scavengers, and in captivity they do just fine with a well-balanced omnivorous diet.

Because they are known to be territorial, you will want to use a tank upwards of 30 gallons if you are mixing them in with other fish.

Rainbow Fish

Rainbow Fish

Rainbow fish, sometimes called blue eyes, are beautiful school fish that you’ve surely seen in many aquariums before.

With over 61 known species of rainbow fish each ranging in their sizes and spectrum of colors, there is a huge variety to choose from. Flake and pellet based diet is appropriate for rainbow fish but should be supplemented with brine shrimp and worms for nourishment.

The smaller species of rainbow fish will grow up to 2.2 inches with other species ranging between 2.5 and 4.5 inches. It is not unheard of to spot a 6 inch adult rainbow fish in captivity, and a school of larger rainbow fish could require up to 100 gallons of water.

Rainbow fish are a good investment as they can last you up to 8 years.

Bristlenose Pleco

Kris (source)

This unique catfish is covered in boney plates and stand out patterns that have made it a sought-after aquarium fish for years.

The bristlenose pleco is easily identifiable by the tentacles found on the head of males and mouths of females. They won’t grow much larger than 4-6 inches and live subterranean lifestyles meaning you will find them at the bottom of your tank often.

They are highly territorial, and you should keep that in mind if you are bunching them together with other fish. If you have several fish that are smaller than the pleco, be aware they may fall victim. Bristlenose plecos do very well in habitats that provide them plenty of coverage, such as caves or foliage.

Bristlenose plecos are herbivores and spirulina and algae are perfect for them, although flakes will do just fine.


Bojan Žavcer (source)

Gouramis hail from Asia and have dazzled fish hobbyists for years with their shape and color patterns.

A Gourami is a labyrinth fish meaning that it is has a lung like organ that allows them to use the atmosphere’s option. This is rather unique for a fish. You can easily recognize them by the long feelers coming from the front of their pelvic fins.

Typically, a gourami isn’t going to grow larger than 3.5 inches long. They can survive in captivity off of a diet of flake food, but the additional nourishment of small insects and larvae is necessary every once in a while for a balanced diet.

For a single gourami, you will want a 10 gallon tank. If you are getting multiple gourami or joining it with the rest of your fish, you will want between 30 and 55 gallons and make sure it stays between 72 and 82 degrees Fahreneheit.


Freshwater fish make for excellent inhabitants to any aquarium because of the wide variety of choices and endless possibilities of combinations.

I recommend looking at what kind of aquarium you have or are planning to upgrade to as well as considering how your new freshwater fish will get along with your others before deciding on the new addition.

Pay close attention to their dietary, temperature and space needs as well as whether or not they would be better off in a school of fish, and your new freshwater fish should liven up your aquarium in no time.

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Jeff Colt

Jeff Colt

Hello, I'm Jeff- an aquarium enthusiast with over 25 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!

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