25 Small Aquarium Fish for Your Freshwater Tank

Mickey Mouse Platy

Platys are colorful fish that are very suitable for beginners. Since they are livebearing fish, many hobbyists start out with only a few fish—which can quickly multiply into many fish. The Mickey Mouse platy is named for a very specific color pattern formed in the tail peduncle. The minimum tank size for this species is 10 gallons.

Other platys include the red wagtail, wagtail, and many more.

Guppy

Guppies are a cornerstone of the small fish aquarium hobby. Another livebearing species, guppy tanks are often overrun with offspring from frequent breeding. The best skill any guppy owner can learn is to tell the difference between males and females to keep populations from exploding. The males are smaller and more colorful fish, while the larger females can have a colorful tail fin but the body is plain with a large white belly.

The more guppies you have, the bigger your tank needs to be. For instance, if you have a 30-gallon tank, you can keep around 15 guppies, but if you have a 10-gallon tank, only about five of them can be kept in it.

Zebra Danio (Zebrafish)

These small, striped fish are one of the few in the aquarium hobby that don't require warm tropical temperatures. Zebrafish are peaceful, community players that love schooling in groups of five or more fish. There are multiple Danio species available in the pet market with a variety of colors and markings. There is a long fin variety of zebra danio, and this fish is also available in glow colors that were developed by adding fluorescent genes into the fish. You’ll need at least a 10-gallon tank for them.

Neon Tetra

One of the most common small freshwater aquarium species is the neon tetra. These fish are known for their colorful appearance with bright red and blue stripes. They are great community fish and school together in a vibrant wave.

The cardinal tetra is another, very similar species. They are distinguishable from the more common neon tetra by their longer red belly bar that extends all the way to the head. The black neon tetra is a similar species with black and gold bars instead of red and blue colors. Depending on the type of tetra you get, you’ll need a 10- or 20-gallon tank at minimum.

White Cloud Mountain Minnow

The white cloud mountain minnow is another species of small community fish that does not require warm tropical temperatures. These fish do well in temperate tanks with zebrafish and goldfish, provided they are not snack size. These fish are commonly added to aquascape setups, where focus is put on the plants, not necessarily the fish, and just a school of one species of fish is added into the aquarium. The minimum tank size for these fish is 10 gallons.

Harlequin Rasbora

The harlequin rasbora is a small, schooling fish with a vibrant ruby coloration, contrasted with a black marking on the back half of the body, giving them the two-toned "harlequin" appearance. These peaceful fish add a bright splash of color to planted or aquascaped tanks. There are also other species of rasbora, like the scissortail, that stay small and do well in community aquariums. If you have a 20-gallon tank, you can house 10 harlequin rasboras in it.

Serpae Tetra

The serpae tetra is a smaller fish with a big personality. These bright red schooling fish with black spots on the body and fins provide color to natural aquascapes with lots of aquatic plants. These fish are very active, and have the habit of biting fins of their friends and tankmates. There is a longfin variety of this fish species that is sometimes available at fish stores. These fish require a minimum tank size of 20 gallons.

Panda Corydoras

The panda corydoras is a common corydoras species seen in the pet trade. These catfish have a white or translucent body with contrasting black spots on the head and tail base, giving them their panda-esque coloration. The minimum tank size for these fish is 10 gallons.

There are multiple species of corydoras catfish with similar, peaceful temperaments. The main differences between these species are their colors and markings. All corydoras are small, peaceful, bottom-dwelling, nocturnal fish species.

Glowlight Tetra

The glowlight tetra is not to be confused with GloFish species. Their coloration comes from natural color patterns and has not been genetically engineered. This is a peaceful schooling tetra that is easy to care for. The translucent, silvery body of the glowlight tetra is divided by an iridescent red-gold stripe running from snout to tail. A 10-gallon tank is all you need, at minimum, for these tetras.

Pea Puffer

A newer addition to the aquarium hobby, the pea puffer is a small but mighty member of the pufferfish family. Don't let their small size trick you! These small fish can be aggressive, even against their own kind. They are usually kept by themselves in a heavily planted aquarium of at least 5 gallons, or two to three can be kept in a 10-gallon aquarium. If keeping them with other fish, those should be small but fast swimming, non-aggressive species.

The pea puffer is not recommended for beginner hobbyists. Proper diet and environment are key in long-term survival of these fish. They are carnivores, so they do well on a diet of frozen bloodworms, brine shrimp, and other meaty foods, and may eat small fish food pellets.

Tiger Barb

The tiger barb is an easy fish to take care of, but they do not play well in community tanks. Be sure they are in a tank with more aggressive fish and have lots of room to swim. They do better when kept in a school of six or more tiger barbs. They need a 20-gallon tank, at minimum.

There are several color variations available, including green and albino. There is a longfin variety that is sometimes available at fish stores, as well as a fluorescent GloFish tiger barb.

Swordtail

Named for the elongated extension of the caudal fin in males, the swordtail is another livebearer fish that can quickly overpopulate a small aquarium. There are many color varieties of swordtail available in the pet fish market. They are peaceful fish, larger than most other livebearers. The females are as colorful as the males but don't have the sword extension on their tail fin. In terms of tanks size, a minimum of 20 gallons is best.

German Blue Ram

There are many species within the cichlid family, but relatively few that stay small in size and can be kept in a community aquarium. The German blue ram is one such species, but is not recommended for beginners given their strict water quality and habitat requirements. They are a beautiful addition to planted aquariums with warm, acidic water conditions. Also, 20 gallons is the minimum tank size for this fish.  

Buenos Aires Tetra

The Buenos Aires tetra is making a comeback in the aquarium hobby. Once known as voracious plant eaters, these colorful fish are being seen more in heavily planted tanks, where plant food is plentiful. These community fish are easy to care for and can tolerate many beginner mistakes. Despite being small, they need a least a 30-gallon tank.

Dwarf Gourami

Of the many gourami species, there are few that stay small. Most gouramis are medium-sized fish, but the dwarf gourami, as the name suggests, tops out at only 2 inches. Like other gouramis, these intermediate-level fish have specific environmental requirements for successful lives. The dwarf gourami can be kept in a community aquarium with other small, peaceful fish species.

The male has brilliant red and blue bands, and the female has more subdued coloration. There are several color varieties of this species, such as the powder blue dwarf gourami, which is all blue and has no red bands. At a minimum, they need a 5-gallon tank.

Gold (Chinese) Barb

Although this fish is green in the wild, they've been captively bred to show brilliant golden coloration. There are a few other colors that have subsequently been bred, including an albino and a tricolor variation. These active fish play well in community tanks, but do prefer slightly less than tropical temperatures.

Gold barbs are schooling fish and should be kept in groups of six or more. Their peaceful nature makes them an excellent choice for community aquariums with tetras, danios, and other small barbs. They should have, at minimum, a 20-gallon tank.

Betta

Betta fish are one of the most common pet fish species. Given their aggressive nature, male bettas must be kept away from other male bettas. However, one male betta can be kept in a community aquarium with fast swimming, non-aggressive fish species. Usually, several females can be kept together in an aquarium with other fish species, but sometimes even female bettas may fight each other. The male and female should only be together when breeding, then the female removed, or the male will bully her and can cause damage.

Betta fish come in a rainbow variety of colors and tail shapes. They should be kept in a spacious tank of 5 to 10 gallons or more, not in a tiny bowl like you find them at pet stores. 

Hachetfish

Looking for a more challenging and rare small fish species? Hatchetfish have a very unique, compressed body shape, and they're known for flying over the top of the water using their wing-like fins. These fish are not for beginners, since they have very specific tank requirements. They will leap out of the water if frightened, so the aquarium must have a secure and tight-fitting lid to keep the fish from flying out. Place these fish in a tank that’s at least 30 gallons.

Congo Tetra

The Congo tetra pushes the maximum length of the small fish category, but these schooling fish are a rainbow addition to many tanks. They are peaceful aquarium fish, with males having longer fins than females. Aim to keep them with other species that are about the same size or smaller. Good examples of tankmates include rainbowfish, swordtails, guppies, and other tetras. Also, keep them in a 30-gallon tank, at a minimum, if you have a smaller school of six fish—larger schools will need a bigger tank.

Beacon Fish

The Beacon fish is another member of the tetra family. Also known as the head and tail light tetra, this fish has distinctive copper spots that resemble lights on a vehicle—one is located at the base of the tail and the other is above the eye. These fish do best in lower lighting with lots of plant cover. The minimum tank size for them is 15 gallons.

Black Phantom Tetra

Rather than bright colors, the black phantom tetra is known for a darker appearance with elongated dorsal fin. The black phantom tetra gets their name from an "eye patch" behind the gills, as if a phantom is peering back at you. But don't worry, despite the name, this is a peaceful schooling fish. These fish make a great contrast with other colorful tetra species that will typically all school together. They require, at minimum, a 10-gallon tank.

Black Ruby Barb

Also known as the purple-headed barb, the black ruby barb has a distinct deep red coloration not commonly seen in other aquarium fish. With a similar body shape as the tiger barb, these fish start with a pale yellow body that deepens with maturity. Adult males are noticeably smaller, slimmer, and more colorful than females. They should be housed in a 30-gallon tank, at a minimum.

Cherry Barb

The cherry barb is named for the male’s bright red color—the female has more subdued coloration that is more orange than red—so they can be a lovely addition to your aquarium if you want to add a colorful fish. These barbs like to be in schools of five or six, at a minimum. They can also be in a peaceful tank with other barbs and tetras. 25 gallons is the minimum tank size for them.

Molly

There are various types of mollies, and they come in a wide range of colors and boast beautiful fins and tails. For example, there are solid black mollies and albino mollies that have red eyes. These small fish are relatively hardy livebearers, and they also prefer being in warmer water, so be sure your temperature is correct for them. These peaceful fish need a minimum tank size of 20 gallons.

Pearl Danio

The pearl danio is easy to care for, as they can tolerate a range of water conditions. They also make a lovely addition to any tank filled with peaceful community fish. And they easily reproduce, so you might get more of them if you care for them properly. These iridescent fish are eye-catching, with their blue-violet body and orange-red stripe that runs from the mid-body to the tail. They should be kept in schools, and the minimum tank size for this species is 20 gallons.