7 Popular Fish you should Try in A 20-Gallon Aquarium


7 Popular Fish You Should Try in a 20-Gallon Aquarium

20-gallon aquariums are one of the most popular tank sizes among fish keepers because they’re small enough to keep in a bedroom but big enough that you can choose from a wide variety of fish to keep. Check out these freshwater fish for a variety of interesting behavior and beautiful colors to spice up your aquarium.


7. Julidochromis

This stunning, three-inch fish is the perfect choice if you’ve ever wanted to try keeping Tanganyikan cichlids. They have the amazing ability to swim vertically, sideways, and upside-down in order to stay close to surfaces and hiding spots. They will feel at home if you provide them with plenty of rockwork that simulates their natural habitat. Depending on the amount you provide cover, you can keep up to six in a 20-gallon-long tank. You could also have one breeding pair in an 20-gallon-high tank. Compared to other African cichlids, Julies are relatively peaceful fish and can cohabitate with other small community fish that prefer swimming in the middle or top of the tank.

Julidochromis, or the golden Julie, is a popular variety because of its vibrant markings and small size.

6. Leopard Danio

You are looking for an interactive fish that is hyper and doesn’t mind saying hello? Look at the leopard danio! This brightly spotted schooling fish looks like a little trout and comes in both short and long fin varieties. This is the best thing about danios – they can live at any temperature without heating and can tolerate a wide range in pH and water hardness. Take six of them and watch their speeding around the tank’s top. To prevent them from hogging all the food, pair them with other fast, midwater fish like tetras and rasboras for a highly entertaining aquarium.

Leopard daanios can be a cost-effective and easy way to school fish. They aren’t as common as their more famous cousin, zebra danio.

5. German Blue Ram

If you are looking for boldly patterned fish, the German blue ram or Mikrogeophagus ramirezi is it. A 20-gallon aquarium can house one male with one or two females for company. A female will have a smaller dorsal fin and a pinkish belly. There are blue spangles in the black spot to her side. A male, on the other hand, is larger, has an extended dorsal ray, and no blue spangles inside his black spot. Keep in mind that the South American dwarf cichlid prefers temperatures above 85 degrees F. So keep them around other hot water fish such as cardinal tetras or Sterbai cory catfish.

German blue rams are monogamous and show parental care for their young. In this picture, the male is on the left, and the female is on the right.

4. Harlequin Rasbora

Trigonostigma heteromorpha another popular schooling fish. They do well in groups of 6-8. Their distinctive black triangular patch and bright orange coloration really stand out in a lushly planted tank. The fish can grow to two inches in length and is easy to care for. For more information on caring for rasboras, read our full care guide.

Harlequin rasboras are social creatures that tend to swim in the middle to top sections of an aquarium.

3. Apistogramma

Apistogramma cacatuoides and Apistogramma agassizii are two of the most popular members of this large genus of South American dwarf cichlids. Apistos are similar to the German blue ram. They are brightly colored and love to be in the bottom third. They also prefer warmer temperatures, around 82 degrees F. If you offer breeding caves, the female can pair up with her male choice, protect her eggs, care for her young, and will even be able to breed. Baby brine shrimp can be used as fry food. Find out more about Apistogramma in our Apistogramma care manual.

The male Apistogramma Cacatuoides has long and brightly-colored dorsal Fins. While his female counterpart is smaller, it turns yellow during spawning.

2. Panda Corydoras

Unlike larger species of cory catfish, Corydoras panda only grows to 1.75 to 2 inches long, so you can easily get a group of six or more for a 20-gallon aquarium. This peaceful bottom dweller can be kept in cooler temperatures from 72 to 77degF. To scavenge their favorite foods such as Repashy gel food and frozen bloodworms, they use the whiskers or barbels around their mouths. You will soon notice breeding behavior and sticky egg coverings in your tank walls if you keep them happy. For more details, read our cory catfish care guide.

Panda Cory Catfish are a crowd favourite because of their distinctive black and white coloration.

1. Pseudomugil gertrudae

The smaller rainbowfish is known to have piercing blue eyes and bright yellow bodies. It also has spotted finnage. A group of six or more male rainbowfish will perform a showy dance with their fins if they are both genders. We chose the spotted blue-eye rainbowfish as our number one pick because of their colorful appearance, interesting behavior, and uniqueness in the hobby. They can be difficult to find and are more expensive depending on where you live. However, if you have a plant tank with them, or a background of black, they will take your breath away.

You could use spawning mops made from yarn to encourage rainbowfish eggs to hatch. After that, you can remove the mop to raise fry in a separate tank.

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