13 Beginner-Friendly Fish For A 20 Gallon Aquarium Tank!

Many people have asked for advice on the best fish to stock in a 20-gallon tank.

Given the wide range of options in the hobby, I decided to publish this article highlighting my favorite fish for a 20-gallon setup.

Apistogrammas

An Apistogramma In Its Tank
An Apistogramma In Its Tank

Pros

  • Colorful
  • Plenty Of Different Options
  • Easy To Feed

Cons

  • Does Better With Dim Lighting
  • Can Be Aggressive
  • Can Be Difficult To Find

Apistogrammas are an excellent choice for 20-gallon tanks due to their manageable size, stunning colors, and intriguing behaviors.

These dwarf cichlids, native to South America, thrive in smaller aquariums, making them a popular choice for both beginners and experienced aquarists.

A 20-gallon tank can comfortably house a pair or a trio of Apistogrammas, typically one male and two females. This setup allows for natural behaviors, such as breeding and territory establishment, without overcrowding the tank.

If you’re aiming for a species-specific tank, you can add a few more individuals, but it’s crucial to provide ample hiding spots and territory to prevent aggression.

Feeding Apistogrammas is relatively straightforward. They prefer a varied diet that includes high-quality flake or pellet food supplemented with live or frozen foods like brine shrimp, daphnia, and bloodworms.

This variety ensures they receive the necessary nutrients for optimal health and vibrant coloration. Regular feedings, once or twice a day, are sufficient to keep them healthy and active.

Apistogrammas thrive in well-planted tanks with plenty of hiding spots such as ceramic pots, caves, and dense vegetation. These elements not only provide security but also enhance the tank’s natural aesthetics.

Water Temperature(22–29°C)
Water FlowLow
pH5.5 – 6.8
Ammonia0
Nitrite0
Nitrate<30
Apistogramma Agassizii Water Parameters

Corydoras

A Corydoras In Its Tank
A Corydoras In Its Tank

Pros

  • Cheap And Easy To Find
  • Plenty Of Color Options
  • Armored Catfish

Cons

  • Need Medium Sized Tanks
  • Need Multiple Corydoras
  • Possess A Mild Venom

Corydoras catfish, often referred to as Cory cats, are excellent fish for a 20-gallon tank due to their peaceful nature, hardy constitution, and bottom-dwelling behavior.

These small, sociable fish are perfect for community tanks and add an element of activity to the lower levels of the aquarium.

In a 20-gallon tank, you can comfortably keep a group of 6-8 Corydoras. They thrive in groups, exhibiting natural schooling behavior that makes them more active and reduces stress.

A well-planted tank with soft substrates like sand or smooth gravel is ideal for Corydoras, as their sensitive barbels can be damaged by rough or sharp substrates. Include hiding spots with decorations like driftwood, rocks, and live plants to provide them with a comfortable environment.

Feeding Corydoras is straightforward; they are omnivores and enjoy a varied diet. High-quality sinking pellets or wafers should form the base of their diet. Additionally, they love to eat live or frozen bloodworms as it mimics their natural diet.

Ensure they receive enough food by observing them during feeding times, as they might not compete well with faster-swimming tank mates.

Corydoras are great for keeping the tank clean as they scavenge the substrate for leftover food, helping to maintain water quality. Their peaceful nature and compatibility with a wide range of other species make them a fantastic addition to any 20-gallon community tank, bringing both utility and charm.

Green Neon Tetras

A Green Neon Tetra In Its Tank
A Green Neon Tetra In Its Tank

Pros

  • Hardy Fish
  • Cheap
  • Easy To Feed

Cons

  • Limited Color Options
  • Difficult To Find In Some Areas
  • Won’t School Much

Green neon tetras are excellent fish for 20-gallon tanks due to their small size, peaceful nature, and striking coloration.

These vibrant fish thrive in well-planted aquariums, which can mimic their natural habitat in the Amazon River basin. A 20-gallon tank provides ample space for a healthy school of green neon tetras, with a recommended stocking number of 10-30 individuals to ensure their schooling behavior, which helps reduce stress and enhances their visual appeal.

A gentle filtration system is crucial to maintain water quality without creating strong currents that can stress these small fish. Moderate lighting is preferred, as it supports plant growth and keeps the tetras comfortable.

Feeding green neon tetras is straightforward, as they are not picky eaters. A balanced diet consisting of high-quality flake or pellet food, supplemented with occasional live or frozen foods like brine shrimp, daphnia, and bloodworms, will keep them healthy and vibrant.

Water Temperature74–82°F (23–28°C)
Water FlowLow
pH3.0 – 6.5
Ammonia0
Nitrite0
Nitrate<30
Green Neon Tetra Water Parameters

Powder Blue Gourami

A Powder Blue Gourami In Its Tank
A Powder Blue Gourami In Its Tank

Pros

  • Peaceful
  • Cheap And Easy To Find
  • Easy To Feed

Cons

  • No Color Alternatives
  • May Have Health Problems
  • Can Be Shy And Hide

Powder Blue Gouramis are a fantastic choice for 20-gallon tanks due to their beautiful color, peaceful demeanor, and manageable size.

As a variant of the dwarf gourami, the powder blue gourami’s striking blue hue adds a splash of color to any aquarium. These fish typically grow to about 2-3 inches in length, making them well-suited for smaller tanks.

A 20-gallon tank is an ideal environment for powder blue gouramis, allowing you to keep a pair or even three of these beautiful fish. The tank setup should include plenty of hiding spots created with live plants, rocks, and driftwood to mimic their natural habitat and reduce stress.

A gentle filtration system is recommended, as these fish prefer calm waters making a cheap sponge filter an excellent option.

Feeding powder blue gouramis is straightforward as they are not fussy eaters. They thrive on a varied diet of high-quality flake food, pellets, and occasional live or frozen foods such as brine shrimp, daphnia, and bloodworms. Offering a balanced diet ensures their vibrant color and overall health.

Feeding them twice daily in small amounts helps maintain water quality and prevent overfeeding.

Water Temperature72–82°F (22–27°C)
Water FlowLow
pH6.0–7.5
Ammonia0
Nitrite0
Nitrate<20
Dwarf Gourami Water Parameters

Guppies

A Guppy In Its Tank
A Guppy In Its Tank

Pros

  • Highly Active Fish
  • Plenty Of Color
  • Cheap
  • Easy To Find

Cons

  • Can Have Poor Genetics
  • AAA Guppies Are Expensive
  • They Breed Very Quickly
  • Some Males Are Aggressive

Guppies are ideal for 20-gallon tanks due to their wide color ranges, lively behavior, and ease of care. These small, hardy fish are perfect for beginners and experienced aquarists alike.

In a 20-gallon tank, you can keep 10-20 male guppies or a breeding group of 3 males and 10 females. Be cautious with breeding setups as guppies reproduce rapidly.

A well-planted tank with live plants like Java fern, Anubias, and Hornwort creates a natural environment for guppies, offering hiding spots and improving water quality. A gentle filtration system and regular water changes are essential to keep the tank clean and free from toxins.

Feeding guppies is simple, as they are omnivores and readily accept various foods. Provide a balanced diet with high-quality flake food, supplemented with live or frozen foods like brine shrimp, daphnia, and bloodworms.

Vegetable matter such as blanched spinach or spirulina flakes is also beneficial. Feed them small amounts twice a day to prevent overfeeding and maintain water quality.

Guppies are active and social fish that bring color and excitement to any aquarium. Their hardy nature and minimal care requirements make them an excellent choice for a 20-gallon tank, allowing aquarists to enjoy their beauty and dynamic behavior with ease.

Water Temperature63-82°F (17 – 28 °C)
Water FlowStill-Low
pH7-8.5
GH8-12 dGH
KH4-8 dKH
Ammonia0
Nitrite0
Nitrate<10ppm
Guppy Water Parameters

Cardinal Tetras

A Cardinal Tetra In Its Tank
A Cardinal Tetra In Its Tank

Pros

  • Hardy
  • Colorful
  • Easy To Find

Cons

  • Slightly Higher Price Tag
  • Don’t School Much
  • Need Plenty Of Swim Space

Cardinal tetras are a fantastic choice for a 20-gallon tank due to their stunning colors, peaceful nature, and compatibility with various tank mates.

Their bright blue and red stripes make them a vibrant addition to any aquarium. In a 20-gallon tank, you can comfortably keep a school of 10-15 cardinal tetras, which allows them to display their natural schooling behavior and feel secure.

A well-planted tank with live plants like Java fern, Amazon swords, and Cryptocoryne provides ample hiding spots and mimics their natural habitat. Cardinal tetras are hardier than the more popular neon tetra but maintaining safe and stable water parameters is still important.

Cardinal tetras are omnivores and should be fed a varied diet. High-quality flake food or micro-pellets make an excellent staple diet, while live or frozen foods like daphnia and cyclops can be offered as treats to enhance their coloration and health.

Feed them small amounts two or three times a day to ensure they receive adequate nutrition without overfeeding. Their peaceful demeanor makes cardinal tetras excellent community fish, compatible with other small, non-aggressive species.

Water Temperature74-84°F (23– 29°C)
Water FlowLow To Moderate
pH3.5 – 7.5
Ammonia0
Nitrite0
Nitrate30
Cardinal Tetra Water Parameters

Rummynose Tetra

A Rummynose Tetra In Its Tank
A Rummynose Tetra In Its Tank

Pros

  • Cheap And Easy To Find
  • Displays Schooling Behaviour

Cons

  • Limited Color Options
  • Pushing 20 Gallon Tank Limits

Rummy Nose Tetras are great fish for a 20-gallon tank due to their striking appearance, peaceful nature, and shoaling behavior.

Their distinctive red noses and black-and-white striped tails make them a visually appealing choice for any aquarium.

In a 20-gallon tank, you can comfortably keep a school of 8-10 Rummy Nose Tetras. These fish thrive in groups, which helps them feel secure and exhibit their natural behaviors.

A well-planted tank with plenty of hiding spots, such as driftwood and live plants, provides an ideal environment for Rummy Nose Tetras. The plants not only offer shelter but also help maintain water quality by absorbing nitrates.

A dark substrate can enhance their colors, making their red noses and striped tails stand out even more.

They do well on a diet of high-quality flake food, supplemented with live or frozen foods like brine shrimp and daphnia. Feeding them a varied diet ensures they receive all the necessary nutrients for optimal health and vibrant colors.

Rummy Nose Tetras are known for their sensitivity to water conditions, so regular maintenance and water changes are essential to keep them healthy. Their peaceful nature makes them an excellent addition to a community tank, where they can coexist with other small, non-aggressive species.

Water Temperature76-80°F (24-27°C)
Water FlowLow To Moderate
pH5.5-7.0
Ammonia0
Nitrite0
Nitrate<30
Rummynose Tetra Water Parameters

German Blue Ram

A German Blue Ram In Its Tank
A German Blue Ram In Its Tank

Pros

  • Colorful Fish
  • Surprisingly Cheap
  • Relatively Peaceful

Cons

  • Sensitive To Water Changes
  • Requires Pristine Water
  • Weakening Genetics

German Blue Rams are beautiful fish for a 20-gallon tank due to their outstanding colors, interesting behavior, and relatively small size.

Their striking blue and gold hues, coupled with their peaceful temperament, make them a visually appealing and harmonious addition to a community aquarium.

In a 20-gallon tank, you can comfortably keep a pair of German Blue Rams. They thrive in pairs, especially during breeding, and their small size (around 2-3 inches) allows them to fit well in smaller tanks.

It’s essential to provide them with a well-structured environment that mimics their natural habitat. A densely planted tank with plenty of hiding spots, such as caves, driftwood, and live plants, provides an ideal environment for German Blue Rams.

They enjoy exploring and establishing territories, so the presence of hiding places helps reduce stress and aggression. A sandy substrate is preferred, as they like to sift through it while foraging.

Regular maintenance and water changes are crucial to keeping German Blue Rams healthy, as they are sensitive to poor water conditions so avoid overfeeding. Their peaceful nature makes them suitable for a community tank, where they can coexist with other small, non-aggressive species.

Water Temperature84-86°F (29-30°C)
Water FlowLow
pH5.0-7.0
Ammonia0
Nitrite0
Nitrate<20
German Blue Ram Water Parameters

Leopard Danios

A Leopard Danio In Its Tank
A Leopard Danio In Its Tank

Pros

  • Hardy Fish
  • Very Active

Cons

  • Can Have Genetic Problems
  • Limited Color Options

Leopard Danios are an excellent choice for 20-gallon tanks due to their hardy nature, active behavior, and striking appearance. Their shimmering, spotted patterns make them a visually appealing addition to any aquarium.

In a 20-gallon tank, you can comfortably keep a school of 6-10 Leopard Danios. They are shoaling fish, which means they thrive in groups, displaying their best colors and natural behaviors when kept together.

Leopard Danios are very hardy and can adapt to a wide range of water conditions, making them perfect for beginners. A well-filtered tank with moderate water flow mimics their natural riverine habitat.

These fish are omnivores and have a voracious appetite. They will readily accept a variety of foods, including high-quality flake or pellet food, live or frozen foods like brine shrimp and daphnia, and even vegetable matter like blanched spinach or zucchini.

Leopard Danios are active swimmers and enjoy a tank with open swimming spaces. Adding plants, both real and artificial, along with rocks and driftwood, can create hiding spots and reduce stress. They are also peaceful and can coexist with a variety of other community fish, making them a versatile choice for mixed-species tanks.

Water Temperature65–77°F (18–25°C)
Water FlowLow
pH6.0 – 8.0
Ammonia0
Nitrite0
Nitrate<30
Leopard Danio Water Parameters

Harlequin Rasboras

Harlequin Rasboras In Their Tank
Harlequin Rasboras In Their Tank

Pros

  • Cheap And Easy To Find
  • Easy To Feed
  • Peaceful

Cons

  • Limited Color Options
  • Does Best Under Dim Light
  • Does Best In A Planted Tank

Harlequin Rasboras are an excellent choice for 20-gallon tanks due to their unique pattern, peaceful nature, and active schooling behavior. Their striking metallic orange and black triangular markings make them a visually appealing addition to any aquarium.

In a 20-gallon tank, you can comfortably keep a school of 8-12 Harlequin Rasboras. They are schooling fish, which means they thrive and feel more secure in groups, displaying their best colors and natural behaviors when kept together.

Harlequin Rasboras are hardy and adaptable, making them suitable for beginners. A well-planted tank with moderate lighting and some open swimming spaces will provide an ideal environment. Adding plants, such as Java fern or Anubias, and some driftwood or rocks for hiding spots can help mimic their natural habitat.

These fish are omnivores and have a diverse diet. They will readily accept high-quality flake or pellet food, as well as live or frozen foods.

Harlequin Rasboras are peaceful and can coexist with a variety of other community fish, making them a versatile choice for mixed-species tanks. Their lively shoaling behavior and stunning appearance can add dynamic activity and beauty to a 20-gallon tank.

Water Temperature70–82°F (21–28 °C)
Water FlowLow
pH5.0 – 7.5
Ammonia0
Nitrite0
Nitrate<20
Harlequin Rasbora Water Parameters

Honey Gourami

A Honey Gourami In Its Tank
A Honey Gourami In Its Tank

Pros

  • Peaceful Fish
  • Bright Yellow Color
  • Cheap And Easy To Find

Cons

  • Likes To Hide
  • Limited Colors
  • Can Jump Out Of Tanks

Honey Gourami are an excellent choice for 20-gallon tanks due to their peaceful nature, unique yellow color, interesting behavior, and ease of care.

Their vibrant golden-yellow bodies and gentle demeanor make them a favorite among both novice and experienced aquarists.

In a 20-gallon tank, you can comfortably keep 2-5 Honey Gouramis. They do well in pairs or small groups but ensure you have at least one female for every male to reduce territorial disputes.

Males are usually more colorful and can become slightly territorial, especially during breeding, but their aggression is minimal compared to other gourami species.

Honey Gouramis prefer a well-planted tank with plenty of hiding spots and gentle filtration. Plants like Java fern, Anubias, and floating plants such as Water Sprite or Duckweed create a natural and comfortable environment for them.

They readily accept high-quality flake or pellet food designed for small tropical fish. To ensure a balanced diet, supplement their diet with live or frozen foods such as brine shrimp, daphnia, and bloodworms.

Honey Gouramis are relatively hardy and adapt well to a variety of water conditions, making them suitable for community tanks. They coexist peacefully with other non-aggressive fish species, adding a splash of color and tranquility to the aquarium.

Water Temperature72–81°F (22–27 °C)
Water FlowLow
pH6.0-7.5
Ammonia0
Nitrite0
Nitrate<30
Honey Gourami Water Parameters

Platy Fish

Platies In Their Tank
Platies In Their Tank

Pros

  • Cheap And Easy To Find
  • Plenty of Color Options
  • Eats Lots Of Different Food

Cons

  • Large Fish
  • Breeds Quickly
  • Can Have Genetic Problems

Platy fish are excellent choices for 20-gallon tanks due to their wide range of colors, peaceful nature, and easy care requirements.

They are ideal for beginners and experienced aquarists alike. In a 20-gallon tank, you can comfortably house 5-7 platies, considering their small size and low bioload.

Platies are omnivores and thrive on a varied diet. They will readily accept high-quality flake food, pellets, and freeze-dried options. Supplement their diet with live or frozen foods such as brine shrimp, daphnia, and bloodworms to ensure they receive a balanced nutrition.

Vegetables like blanched spinach or zucchini can also be offered occasionally with some platy fish loving them and others ignoring them.

Setting up a tank for platies is straightforward. They prefer a well-planted aquarium with plenty of hiding spots created by decorations or plants like java fern, anubias, and hornwort. A moderate flow filter is recommended to keep the water clean, but ensure it’s not too strong as platies prefer calm waters.

Platies are livebearers, meaning they give birth to free-swimming fry. If you don’t want a population boom, consider keeping only males or using a separate breeding tank for females.

Their peaceful temperament makes them great community fish, cohabiting well with other non-aggressive species like tetras, guppies, and corydoras. Platies’ hardy nature and adaptability make them an excellent choice for a thriving 20-gallon aquarium.

Water Temperature68-79°F (20-26°C)
Water FlowLow – Moderate
pH7.0-8.2
Ammonia0
Nitrite0
Nitrate<30
Platy Water Parameters

Neocaridina Shrimp

Types Of Neocaridina
Types Of Neocaridina

Pros

  • Eat Soft Algae
  • Can Be Colorful
  • Cheap And Easy To Find

Cons

  • Some Fish Eat Them
  • May Be Sensitive To Water
  • Some People Don’t Like Shrimp

Neocaridina shrimp are underrated for 20-gallon tanks due to their vibrant colors, low bioload, and fascinating behaviors.

These shrimp are ideal for beginners and seasoned aquarists alike. In a 20-gallon tank, you can easily start with 20-40 Neocaridina shrimp but they will breed and the available food will manage their population.

Feeding Neocaridina shrimp is simple. They are omnivores and thrive on a diet of high-quality shrimp pellets, algae wafers, and blanched vegetables like spinach or zucchini. They also consume biofilm, soft algae, and detritus in the tank, helping to keep the aquarium clean.

Setting up a tank for Neocaridina shrimp involves providing plenty of hiding spots and surfaces for them to graze on. Live plants such as java moss, floating plants, and stem plants are excellent choices, offering both shelter and additional grazing surfaces.

Ensure the tank has gentle filtration to avoid sucking in the tiny shrimp; sponge filters are ideal for this purpose.

Neocaridina shrimp are peaceful and make great additions to community tanks with small, non-aggressive fish like tetras or guppies.

Their breeding is straightforward, and they reproduce readily in well-maintained tanks, making them a delightful and dynamic addition to any 20-gallon aquarium.

Water Temperature65-80°F (18.5-27°C)
Water FlowStill-Low
pH6.7-8
GH6-10 dGH
KH3-10 dKH
Ammonia0 ppm
Nitrite0 ppm
Nitrate<20ppm
Red Cherry Shrimp Water Parameters

Conclusion

Choosing the right fish for your 20-gallon tank can make all the difference in creating a vibrant and harmonious aquatic environment.

From the colorful Apistogrammas and active Leopard Danios to the peaceful Honey Gouramis and versatile Neocaridina Shrimp, each species offers unique benefits that cater to different aquarium setups and preferences.

By considering factors like temperament, diet, and habitat needs, you can create a thriving community of fish that not only enhances the beauty of your tank but also provides endless enjoyment and learning opportunities.

Whether you’re a beginner or an experienced aquarist, these beginner-friendly fish are excellent choices to help you achieve a balanced and lively 20-gallon aquarium.