20 Best Freshwater Fish for 20-Gallon Tanks
Find out which are the best freshwater fish species that can be kept in a 20-gallon (76-liter) tank. In this article, we will most common species, their requirements, feeding habits, lifespan and behavior. Read on to learn about these wonderful aquatic creatures!
Neon Tetra
Neon Tetras are arguably one of the most popular freshwater fish due to their stunning colors and easy care requirements. They are shoaling fish, meaning they’re best suited for a group of at least six.
- Min. Tank Size: 10 gallons (38 liters) for a small school
- Care Level: Easy
- Adult Size: 1.5 inches (3.8 cm)
- Temperature: 72-80°F (22-26°C)
- Diet & Feeding: Omnivorous; flakes, pellets, and live/frozen foods
- Lifespan: 5-8 years
- Behavior: Peaceful; suitable for community tanks
Neon Tetras make an excellent addition to 20-gallon tanks and bring captivating colors to your aquarium.
Black Molly
Black Mollies are livebearers known for their sleek, all-black bodies and peaceful demeanor. They adapt well to various tank conditions and are perfect for beginner and experienced aquarists.
- Min. Tank Size: 20 gallons (76 liters) for a small group
- Care Level: Easy
- Adult Size: 3 inches (7.6 cm)
- Temperature: 70-80°F (21-26°C)
- Diet & Feeding: Omnivorous; flakes, pellets, and live/frozen foods
- Lifespan: 3-5 years
- Behavior: Peaceful; suitable for community tanks
Black Mollies enjoy swimming in small groups and add a striking contrast to your 20-gallon tank with their all-black appearance.
Guppy Fish
Guppies are a highly popular and colorful fish choice for aquarium hobbyists. Known for their fancy tails, they add a touch of elegance and vibrancy to any 20-gallon tank.
- Min. Tank Size: 10 gallons (38 liters) for a small group
- Care Level: Easy
- Adult Size: 1-2.5 inches (2.5-6.4 cm)
- Temperature: 72-82°F (22-28°C)
- Diet & Feeding: Omnivorous; flakes, pellets, and live/frozen foods
- Lifespan: 2-3 years
- Behavior: Peaceful; suitable for community tanks
Guppy Fish breed rapidly, so it’s essential to keep an eye on their population to prevent overcrowding in your 20-gallon tank.
Dwarf Gourami
Dwarf Gouramis are vibrantly colored fish with a peaceful temperament. They’re an excellent choice for a 20-gallon tank, especially when designing a planted or community aquarium.
- Min. Tank Size: 10 gallons (38 liters) for a pair
- Care Level: Easy
- Adult Size: 3.5 inches (8.9 cm)
- Temperature: 72-82°F (22-28°C)
- Diet & Feeding: Omnivorous; flakes, pellets, and live/frozen foods
- Lifespan: 4-6 years
- Behavior: Peaceful; suitable for community tanks
Dwarf Gouramis appreciate a well-planted tank with hiding spots, as they can be shy. They do well with other peaceful species in a 20-gallon tank.
Zebra Danio
Zebra Danios are a popular choice for 20-gallon tanks due to their appealing striped pattern, active swimming, and hardy nature. They thrive in schools, making them perfect for community tanks.
- Tank Size: 10 gallons (38 liters) for a small school
- Care Level: Easy
- Adult Size: 2 inches (5 cm)
- Temperature: 65-77°F (18-25°C)
- Diet & Feeding: Omnivorous; flakes, pellets, and live/frozen foods
- Lifespan: 3-5 years
- Behavior: Peaceful; suitable for community tanks
Zebra Danios are highly adaptable, active swimmers that bring a sense of energy to your 20-gallon aquarium. Remember to provide ample swimming space for them to thrive.
Platies
Platies are a popular livebearer species appreciated for their colorful varieties and hardy nature. They’re well-suited for 20-gallon tanks and a great choice for both beginners and experienced aquarists.
- Min. Tank Size: 10 gallons (38 liters) for a small group
- Care Level: Easy
- Adult Size: 2-3 inches (5-7.6 cm)
- Temperature: 70-80°F (21-27°C)
- Diet & Feeding: Omnivorous; flakes, pellets, and live/frozen foods
- Lifespan: 3-5 years
- Behavior: Peaceful; suitable for community tanks
When keeping Platies, it’s crucial to monitor their population, as they can breed rapidly. Providing a well-balanced diet and stable water conditions will ensure their optimal health.
Swordtail
Swordtails are known for their striking sword-like tails and vibrant colors. This beautiful livebearer species is an excellent addition to any 20-gallon tank featuring community fish.
- Min. Tank Size: 20 gallons (76 liters)
- Care Level: Easy
- Adult Size: 4 inches (10 cm)
- Temperature: 72-82°F (22-28°C)
- Diet & Feeding: Omnivorous; flakes, pellets, and live/frozen foods
- Lifespan: 3-5 years
- Behavior: Peaceful; suitable for community tanks
Swordtails should be kept in an environment with plenty of hiding spots and vegetation, as they appreciate coverage. Make sure to monitor their breeding habits to prevent tank overcrowding.
Corydoras Catfish
Corydoras Catfish are a small, bottom-dwelling species adored for their unique appearance and friendly, social nature. They are a great addition to a 20-gallon tank, functioning as natural tank cleaners.
- Min. Tank Size: 20 gallons (76 liters) for a small group
- Care Level: Easy
- Adult Size: 2-3 inches (5-7.6 cm)
- Temperature: 72-79°F (22-26°C)
- Diet & Feeding: Omnivorous; sinking pellets, live, and frozen foods
- Lifespan: 3-5 years
- Behavior: Peaceful; suitable for community tanks
Corydoras Catfish should be kept in a group of at least six and provided with sand or smooth gravel substrate to prevent damage to their delicate barbels.
Betta Fish
Betta Fish, often known as Siamese Fighting Fish, are famed for their stunning colors and flowing fins. They make a beautiful addition to a 20-gallon tank, especially when paired with well-suited tank mates.
- Min. Tank Size: 5 gallons (19 liters)
- Care Level: Easy
- Adult Size: 2-3 inches (5-7.6 cm)
- Temperature: 76-82°F (24-28°C)
- Diet & Feeding: Carnivorous; pellets, live, and frozen foods
- Lifespan: 3-5 years
- Behavior: Can be aggressive; choose tank mates carefully
While Betta Fish can be territorial, a larger tank size like a 20-gallon provides enough space to coexist with other peaceful fish species, provided each fish has a designated territory.
Harlequin Rasbora
Harlequin Rasboras are small tropical fish characterized by their bright orange color and contrasting black triangular patch. They’re a great addition to a 20-gallon tank due to their vibrant appearance and peaceful demeanor.
- Min. Tank Size: 20 gallons (76 liters) for a small school
- Care Level: Easy
- Adult Size: 1.5-2 inches (3.8-5 cm)
- Temperature: 72-80°F (22-26°C)
- Diet & Feeding: Omnivorous; flakes, pellets, and live/frozen foods
- Lifespan: 5-8 years
- Behavior: Peaceful; suitable for community tanks
For a harmonious tank, keep Harlequin Rasboras in schools of at least eight. They thrive in a well-planted aquarium with ample hiding spots, swimming space, and stable water conditions.
Ember Tetra
Ember Tetras are small, beautifully colored fish with a peaceful temperament. Their fiery orange coloring adds a vibrant touch to your 20-gallon tank, especially in a planted aquarium setup.
- Min. Tank Size: 10 gallons (38 liters) for a small school
- Care Level: Easy
- Adult Size: 0.8 inches (2 cm)
- Temperature: 73-84°F (23-29°C)
- Diet & Feeding: Omnivorous; flakes, pellets, and live/frozen foods
- Lifespan: 2-4 years
- Behavior: Peaceful; suitable for community tanks
Ember Tetras should be kept in a shoal of at least six and provided with a well-planted tank environment that offers plenty of hiding spots and swimming areas to ensure their well-being.
Cherry Barb
Cherry Barbs are a small, peaceful fish with striking red and silver colors. They are an excellent choice for 20-gallon tanks due to their easy care requirements and compatibility with other peaceful fish species.
- Min. Tank Size: 20 gallons (76 liters) for a small school
- Care Level: Easy
- Adult Size: 2 inches (5 cm)
- Temperature: 73-81°F (23-27°C)
- Diet & Feeding: Omnivorous; flakes, pellets, and live/frozen foods
- Lifespan: 4-6 years
- Behavior: Peaceful; suitable for community tanks
To ensure your Cherry Barbs thrive in your 20-gallon tank, it’s best to keep them in groups of six or more and provide a well-planted environment with lots of hiding spaces.
Endler’s Livebearer
Endler’s Livebearers are a vibrant, hardy, and active fish species. Their small size and lively nature make them a great addition to your 20-gallon tank.
- Min. Tank Size: 5 gallons (19 liters) for a small group
- Care Level: Easy
- Adult Size: 1-1.5 inches (2.5-3.8 cm)
- Temperature: 75-81°F (24-27°C)
- Diet & Feeding: Omnivorous; flakes, pellets, and live/frozen foods
- Lifespan: 2-3 years
- Behavior: Peaceful; suitable for community tanks
Endler’s Livebearers thrive in groups, so keep them in numbers of six or more to ensure their well-being. As prolific breeders, ensure you monitor their population to avoid overcrowding within the tank.
Bolivian Ram
Bolivian Rams are a peaceful cichlid species known for their interesting appearance and temperament. They make an excellent addition to community tanks and work well with other compatible species.
- Min. Tank Size: 20 gallons (76 liters)
- Care Level: Moderate
- Adult Size: 3 inches (7.6 cm)
- Temperature: 72-79°F (22-26°C)
- Diet & Feeding: Omnivorous; flakes, pellets, and live/frozen foods
- Lifespan: 4-6 years
- Behavior: Peaceful; suitable for community tanks
To ensure your Bolivian Ram thrives in a 20-gallon tank, provide a well-planted environment with ample hiding spots, smooth rocks, and sandy substrate. This setup will help mimic their natural habitat, keeping them happy and healthy.
Pearl Danio
Pearl Danio is a small and beautiful freshwater fish that makes a perfect addition to a 20-gallon tank. This species comes from South Asia and is known for its striking appearance, characterized by a shimmering iridescent sheen on their body.
- Min. Tank Size: 20 gallons (76 liters) for a small school
- Care Level: Easy
- Adult Size: 2 inches (5 cm)
- Temperature: 68-77°F (20-25°C)
- Diet & Feeding: Omnivore, including flakes and small live or frozen foods
- Lifespan: Up to 5 years
- Behavior: Peaceful, active, and schooling fish
These fish prefer to swim in the middle of the tank, so they make a great choice if you want some activity in that area. It’s best to keep them in groups of at least six, as they feel more secure and display more interesting behaviors that way.
White Cloud Minnow
The White Cloud Minnow is a fantastic option for a 20-gallon tank, especially for beginners, because they are hardy and low-maintenance fish. Originating from China, these fish display a stunning mix of iridescent blue, gold, and red colors.
- Min. Tank Size: 10 gallons (38 liters) for a small school
- Care Level: Easy
- Adult Size: 1.5 inches (3.8 cm)
- Temperature: 64-72°F (18-22°C)
- Diet & Feeding: Omnivore, primarily eating flakes, small live, and frozen food
- Lifespan: 3 to 5 years
- Behavior: Peaceful and active schooling fish
White Cloud Minnows enjoy swimming in a densely planted environment, which closely mimics their natural habitat. Be sure to keep them in groups of at least six to showcase their beautiful schooling behavior and help them feel more secure in their surroundings.
Kuhli Loach
Kuhli Loach is a captivating and unique addition to your 20-gallon tank. Hailing from Southeast Asia, these eel-like fish have a snake-like appearance with alternating bands of black and bright orange or yellow.
- Min. Tank Size: 20 gallons (76 liters)
- Care Level: Easy to moderate
- Adult Size: 4 inches (10 cm)
- Temperature: 73-86°F (23-30°C)
- Diet & Feeding: Omnivore, enjoying sinking pellets, wafers, and live or frozen foods
- Lifespan: Up to 10 years
- Behavior: Peaceful, nocturnal, and bottom-dwelling
Kuhli Loaches are best kept in groups to display their intriguing social behaviors. Provide them with a well-planted and dimly-lit environment, along with hiding spots such as rocks and cave-like structures, so they can seek shelter and feel secure. These loaches are great at cleaning up uneaten food and reducing debris in the tank.
Celestial Pearl Danio
Celestial Pearl Danios, also known as Galaxy Rasboras, are charming little fish with eye-catching colors and patterns that will surely brighten up any 20-gallon tank. These fish originate from Myanmar and are known for their vibrant celestial blue spots on a dark blue body.
- Min. Tank Size: 10 gallons (38 liters) for a small school
- Care Level: Easy
- Adult Size: 1 inch (2.5 cm)
- Temperature: 73-78°F (23-26°C)
- Diet & Feeding: Omnivore, relishing a variety of flakes, small live, and frozen foods
- Lifespan: Up to 3 years
- Behavior: Peaceful, active, and schooling fish
Celestial Pearl Danios can be shy, so it’s important to keep them in a group of at least six to help them feel more comfortable. They also appreciate a densely planted tank with hiding spots and subdued lighting to recreate their natural environment.
Sparkling Gourami
Sparkling Gourami is an enchanting freshwater fish that will add a magical touch to your 20-gallon tank. This species, native to Southeast Asia, has a dazzling iridescent shine that makes them a highly sought-after choice for aquarium enthusiasts.
- Min. Tank Size: 10 gallons (38 liters) for a pair
- Care Level: Easy
- Adult Size: 1.5 inches (3.8 cm)
- Temperature: 75-81°F (24-27°C)
- Diet & Feeding: Omnivore, enjoying a mix of flakes, small live, and frozen foods
- Lifespan: 3 to 5 years
- Behavior: Peaceful, curious, and moderately active
These fish are known for their ability to breathe air directly. It’s essential to provide a well-planted tank with access to the surface for your Sparkling Gourami, as they need to gulp air occasionally. Keep them in small groups to observe their playful and engaging social interactions.
Otocinclus Catfish
Otocinclus Catfish, also known as Dwarf Suckermouth Catfish, are an excellent addition to your 20-gallon tank. These small fish originate from South America and are highly efficient algae eaters, which helps keep the tank clean.
- Min. Tank Size: 20 gallons (76 liters) for a small group
- Care Level: Easy
- Adult Size: 2 inches (5 cm)
- Temperature: 72-79°F (22-26°C)
- Diet & Feeding: Herbivore, primarily feeding on algae and veggie tablets
- Lifespan: 3 to 5 years
- Behavior: Peaceful, active, and social
Otocinclus Catfish are best kept in groups of at least four to six, as they thrive in communities of their own kind. Provide a well-planted tank with hiding spots and a gentle water flow to closely mimic their natural habitat. These fish get along well with other peaceful tankmates, making them a great addition to a community tank.
Tips for Choosing Fish for 20-Gallon Aquarium
When starting out with a 20-gallon aquarium, it’s crucial to know what type of fish to choose. Here are some helpful tips for selecting the best freshwater fish for your 20-gallon tank:
- Consider the fish size. Choose smaller fish that will not outgrow the tank; look for species that stay under 6 inches in length.
- Think about compatibility. Ensure that the fish species you pick get along well with others in the community and don’t have aggressive tendencies.
- Evaluate the activity level. Opt for fish with similar activity levels to ensure that all inhabitants have enough space and feel comfortable in their new home.
- Check the water requirements. Select fish that have similar water parameter needs, such as temperature, pH, and hardness levels.
- Take note of the fish’s diet. Pick fish species that eat similar foods, making feeding time simpler and maintaining the cleanliness of the tank.
- Research the fish’s behavior. Some fish are nocturnal or have unique habits that may not work with your aquarium setup or other species in the tank.
- Remember the schooling factor. Some fish are happier and feel safer in a group, so choose species that can form schools or small communities.
With these tips in mind, you can confidently select fish that will thrive in your 20-gallon tank, ensuring a healthy, harmonious, and visually appealing aquatic environment.
Conclusion
In summary, choosing any of these fascinating freshwater fish for your 20-gallon tank will enliven your aquarium and create a harmonious environment. Remember to follow the care guidelines for each species to ensure a happy and healthy aquatic community. Which fish will you choose? Let us know in the comments below!
