HomeFreshwater FishFreshwater Aquarium Basics19+ Amazing Fish for 20 Gallon Tank (With Pictures)

19+ Amazing Fish for 20 Gallon Tank (With Pictures)

A 20-gallon Aquarium is a great option for those who want to keep live plants and freshwater fish species without taking up too much space. However, it’s important to stock the tank wisely to ensure its success.

When choosing the best fish for your 20-gallon tank, it’s not just about knowing which fish grow to an appropriate size. You also need to consider the temperament and needs of any fish you keep and ensure that they are compatibility with each other.

In this guide, National Park Aquarium will introduce you to the 17 best fish species for a 20-gallon tank, including “Schooling Fish, Bottom Dwellers, Centerpiece Fish, Colorful Fish, Unique and Uncommon Fish” that you can keep and provide you with some useful advice on selecting and maximizing the potential of your tank.

Small Schooling Fish for 20 Gallon Tank

If you’re looking for small schooling fish that are beginner-friendly, here are some options that you might want to consider:

  • Neon Tetras
  • Zebra Danios
  • GloFish
  • Guppies

1. Neon Tetras

coolest fish for 20 gallon tank
coolest fish for 20 gallon tank

Neon Tetras are small, colorful, and easy to maintain. Their size, peaceful temperament, and preference for schooling make them perfect for a 20-gallon tank, allowing them to thrive and exhibit their beautiful colors.

  • Size: Up to 1.5 inches
  • Minimum tank size: 10 gallons
  • Care level: Easy
  • Temperament: Peaceful
  • Schooling/shoaling fish: Yes, they enjoy being in groups.
  • Temperature: 70°-81°F
  • Diet: Omnivorous
  • How Many?: 8-10

2. Zebra Danios

Zebra Danios fish for 20 gallon aquarium
Zebra Danios fish for 20 gallon aquarium

Zebra Danios are colorful and beautiful, lively, and easy to care for. They prefer to be in groups, making a 20-gallon tank a suitable habitat that offers enough space for them to school and engage in their active swimming patterns.

  • Size: Up to 2 inches
  • Minimum tank size: 10 gallons
  • Care level: Easy
  • Temperament: Peaceful
  • Schooling/shoaling fish: Yes, they enjoy company.
  • Temperature: 65°-77°F
  • Diet: Omnivorous
  • How Many?: 5-6

3. Guppies

fish for 20 gallon freshwater tank
fish for 20 gallon freshwater tank

These tiny yet vibrant creatures thrive in spacious environments like your 20-gallon tank. Their easy maintenance and adaptability make them a perfect fit. Their fondness for group living adds a lively dynamic to your aquarium.

  • Size: 1.5-2 inches
  • Minimum tank size: 5 gallons
  • Care level: Easy
  • Temperament: Peaceful
  • Schooling/shoaling fish: Yes, they love company!
  • Temperature: 74°-82°F
  • Diet: Omnivorous
  • How Many?: 5-6

4. GloFish

GloFish in 20 gallon fish tank
GloFish in 20 gallon fish tank

GloFish are genetically engineered to glow, adding a burst of color to any tank. A 20-gallon tank provides them with enough space to school and exhibit their vibrant colors, making the tank visually captivating.

  • Size: Up to 2 inches
  • Minimum tank size: 5 gallons
  • Care level: Moderate
  • Temperament: Peaceful
  • Schooling/shoaling fish: Yes, they prefer to be in groups.
  • Temperature: 72°-82°F
  • Diet: Omnivorous
  • How Many?: 6

Bottom Dwellers in 20-Gallon Tank

If you’re looking for bottom-dwelling fish, here are some options that you might want to consider:

  • Kuhli Loaches
  • Corydoras Catfish

5. Kuhli Loaches

Kuhli Loaches, also known as leopard loach or coolie loach, are small bottom-dwelling eel-like fish fish that live peacefully in freshwater that are known for their peaceful temperament and unique appearance. They belong to the Cobitidae family and are native to Southeast Asia.

Kuhli Loaches for 20 gallon tank
Kuhli Loaches for 20 gallon tank
  • Size: 3-5 inches
  • Tank size: 20 gallons or more
  • Care level: Easy
  • Temperament: Peaceful
  • Temperature: 75°F – 86°F
  • Diet: Omnivorous
  • How many?: 4-5

6. Corydoras Catfish

unique fish for 20 gallon tank
unique fish for 20 gallon tank

Corydoras Catfish are sociable bottom dwellers. A 20-gallon tank is perfect for a small school of these catfish as it provides enough space for them to rummage around the bottom while cohabiting peacefully with other fish species.

  • Size: Up to 2 inches
  • Minimum tank size: 20 gallons
  • Care level: Easy
  • Temperament: Peaceful
  • Temperature: 72°-78°F
  • Diet: Omnivorous
  • How Many?: 4-6

Centerpiece Fish for 20 Gallon Tank

A 20-gallon tank is a great size for a home aquarium. If you’re looking for a centerpiece fish to make your tank stand out, there are many options to choose from. Some good options include dwarf gouramis, Striped Panchax, Bolivian Ram, Rosy Barb. All of these species have bright colors and interesting patterns that will bring focus to the center of the tank.

7. Dwarf Gouramis

colorful freshwater fish for 20-gallon tank
colorful freshwater fish for 20-gallon tank

Dwarf Gouramis are colorful and peaceful. The spaciousness of a 20-gallon tank allows them to comfortably share space with other peaceful fish, and their striking colors add beauty to the tank.

  • Size: Up to 3.5 inches
  • Minimum tank size: 10 gallons
  • Care level: Easy
  • Temperament: Peaceful
  • Temperature: 72°-82°F
  • Diet: Omnivorous
  • How Many?: 1-2

8. Striped Panchax

Striped Panchax is a peaceful surface-dwelling fish that originates from the rivers and streams of India and Sri Lanka. They are perfect for a community tank of 20 gallon, provided that the other fish in there aren’t small enough to fit in its mouth.

Striped Panchax Fish for 20 gallon tank
Striped Panchax Fish
  • Size: Up to 2.5 inches
  • Minimum Tank Size: 10 gallons
  • Care Level: Moderate
  • Temperament: Peaceful
  • Temperature: 72°F to 77°F
  • Diet: Omnivorous
  • How many?: 1-2

9. Bolivian Ram

Bolivian Ram, also known as Mikrogeophagus altispinosus, is a peaceful fish species that pairs well with Rosy Barbs. They are known for their lively yet non-aggressive demeanor, adding variety and a sense of tranquility to 20 gallon aquariums.

Bolivian Ram fish for 20 gallon tank
Bolivian Ram
  • Size: Up to 3 inches
  • Minimum Tank Size: 20 gallons
  • Care Level: Moderate
  • Temperament: Peaceful
  • Temperature: 72°F to 79°F
  • Diet: Omnivorous
  • How many?: 2

10. Rosy Barb

Rosy Barb is a schooling fish that is peaceful and active swimmers. They are perfect for a 20-gallon tank, allowing them to thrive and exhibit their beautiful colors.

Rosy Barb for 20 gallon tank
Rosy Barb Fish
  • Size: Up to 6 inches
  • Minimum Tank Size: 20 Gallons
  • Care Level: Easy
  • Temperament: Peaceful
  • Temperature: 64°F to 72°F
  • Diet: Omnivorous
  • How many?: 5

Hardy and Low-Maintenance Fish for 20 Gallon Tank

Some hardy and low-maintenance fish that would be great for a 20-gallon tank, include platy and mollies fish.

11. Platy Fish

community fish for 20 gallon tank
community fish for 20 gallon tank

Platies are compact, resilient fish available in numerous hues. They have a calm demeanor and get along well with other non-aggressive fish. Similar to guppies, they’re an excellent choice for those just starting in the hobby.

  • Size: Up to 3 inches
  • Minimum tank size: 10 gallons
  • Care level: Easy
  • Temperament: Peaceful
  • Temperature: 70-78°F (21-26°C)
  • Diet: Omnivorous
  • How Many?: 5-6

12. Mollies Fish

schooling fish for 20 gallon tank
schooling fish for 20 gallon tank

Mollies are relatively easy to care for and peaceful. A 20-gallon tank is their minimum requirement, giving them ample room to swim freely and school with their peers, making for a lively and dynamic tank.

  • Size: 3-4 inches
  • Minimum tank size: 20 gallons
  • Care level: Easy
  • Temperament: Peaceful
  • Temperature: 70°-82°F
  • Diet: Omnivorous
  • How Many?: 3-5

Unique and Uncommon Fish for 20 Gallon Aquarium

If you’re looking for unique fish to add to your 20-gallon aquarium, there are many options to choose from. Some uniqu fish include Scarlet Badis, Sparkling Gourami.

13. Scarlet Badis

Scarlet Badis (Dario dario) is a small freshwater fish species that is native to the tributaries of the Brahmaputra river in West Bengal, India. Scarlet Badis are known for their stunning colors and patterns that cover their bodies.

Scarlet Badis fish for 20 gallon tank
Scarlet Badis
  • Size: Up to 1 inch
  • Minimum Tank Size: 5 gallons
  • Care Level: Moderate to difficult
  • Temperament: Peaceful
  • Temperature: 72°F to 79°F
  • Diet: Carnivorous
  • How many?: 3-4

14. Sparkling Gourami

The Sparkling Gourami (Trichopsis pumila), unique and peaceful, is a small freshwater fish originating from ponds, slow rivers, and rice fields in Southeast Asia. They are known for their iridescent scales and the ability to create a shimmering effect as they move.

Sparkling Gourami fish for 20 gallon tank
Sparkling Gourami Fish
  • Size: Up to 1.5 inches.
  • Minimum Tank Size: 10 gallons.
  • Care Level: Easy.
  • Temperament: Peaceful and shy.
  • Temperature: 72°F to 82°F
  • Diet: Omnivorous
  • How many?: 2-3

7 Best Saltwater Fish for 20-Gallon Tank

Here’s a list of fish you can add to a 20-gallon saltwater tank, especially for beginners.

  • Clownfish
  • Firefish
  • Royal Gramma
  • Pajama Cardinalfish
  • Watchman Goby
  • Neon Blue Goby
  • Flame Angelfish

15. Clownfish for 20 Gallon Aquarium

saltwater fish for a 20 gallon tank
saltwater fish for a 20 gallon tank

Clownfish are popular and charming. Their size, temperament, and diet make them well-suited for a 20-gallon tank, allowing enough space for a pair to thrive and display their vibrant colors.

  • Size: 3-4 inches
  • Minimum tank size: 20 gallons
  • Care level: Moderate
  • Temperament: Semi-aggressive
  • Temperature: 75°-82°F
  • Diet: Omnivorous
  • How Many?: 1-2

16. Firefish

Firefish ideas for 20 gallon aquarium
Firefish ideas for 20 gallon aquarium

Firefish are peaceful and vibrant, and a 20-gallon tank gives them sufficient space to live comfortably.

Their diet preference and love for a solitary life make them a good choice for a 20-gallon tank.

  • Size: Up to 3 inches
  • Minimum Tank Size: 20 gallons
  • Care Level: Moderate
  • Temperament: Peaceful and prefers solitude
  • Temperature: 72°F-82°F
  • Diet: Carnivorous
  • How Many?: 1

17. Royal Gramma

Best fish to try for your 20 gallon aquarium
Best fish to try for your 20 gallon aquarium

A single Royal Gramma is ideal for a 20-gallon tank. Their size, peaceful nature, and diet make them a suitable choice, allowing enough room for them to display their striking colors.

  • Size: Up to 3 inches
  • Minimum Tank Size: 20 gallons
  • Care Level: Easy
  • Temperament: Peaceful
  • Temperature: 72°F-78°F
  • Diet: Carnivorous
  • How Many?: 1

18. Pajama Cardinalfish

Pajama Cardinalfish Image
Pajama Cardinalfish Image

Pajama Cardinalfish are peaceful and easy to care for. The spaciousness of a 20-gallon tank offers them enough room to school and live comfortably.

  • Size: Up to 3.5 inches
  • Minimum Tank Size: 20 gallons
  • Care Level: Easy
  • Temperament: Peaceful
  • Temperature: 72°F-78°F
  • Diet: Carnivorous
  • How Many?: 1

19. Watchman Goby

Watchman Goby IMG
Watchman Goby IMG

Watchman Goby is peaceful and easy to maintain. A 20-gallon tank provides ample space for it to live comfortably, making it a suitable choice for such a tank.

  • Size: Up to 3 inches
  • Minimum Tank Size: 20 gallons
  • Care Level: Easy
  • Temperament: Peaceful
  • Temperature: 72°F-78°F
  • Diet: Carnivorous
  • How Many?: 1

20. Neon Blue Goby

Neon Blue Goby in 20 gallon tank
Neon Blue Goby in 20 gallon tank

Neon Blue Goby are small, vibrant, and peaceful. Their size, diet, and non-schooling nature make a 20-gallon tank a suitable home for them, giving them ample space to thrive and exhibit their bright colors.

  • Size: Up to 2 inches
  • Minimum Tank Size: 20 gallons
  • Care Level: Moderate
  • Temperament: Peaceful
  • Temperature: 72°F-78°F
  • Diet: Carnivorous
  • How Many?: 1

21. Flame Angelfish

predatory fish for 20 gallon tank
predatory fish for 20 gallon tank

A single Flame Angelfish is suitable for a 20-gallon tank. Their size, semi-aggressive temperament, and diet make them a great choice, providing enough space for them to showcase their vibrant colors.

  • Size: Up to 4 inches
  • Minimum Tank Size: 20 gallons
  • Care Level: Moderate
  • Temperament: Semi-aggressive
  • Temperature: 72°F-78°F
  • Diet: Omnivorous
  • How Many?: 1

Tips for Choosing Fish for 20-Gallon Aquarium

A 20-gallon aquarium provides ample space for a variety of fish, but it’s essential to choose species that are suitable for this tank size and can coexist harmoniously. Below are some tips and fish recommendations for a 20-gallon aquarium:

Consider the fish’s adult size

Avoid purchasing fish that will grow too large for a 20 gallon tank. Instead, look for species that remain relatively small throughout their lives.

Keep in mind the fish’s temperament

Some fish are peaceful and can coexist with others, while some can be aggressive or territorial. Research the temperaments of your chosen species to ensure they get along.

Factor in swimming space and territory

Mid-water swimmers, bottom-dwellers, and surface swimmers can be combined to utilize different sections of the aquarium.

Think about maintenance and care levels

Some fish have specific water parameters and dietary requirements, so ensure you can provide for their needs.

Research compatibility

Some fish might have specific requirements or might not get along with certain other species. It’s always a good idea to check which species can coexist peacefully.

Conclusion

Choosing the fish for 20 gallon tank involves careful consideration of compatibility, size, behavior, and the specific needs of each species. It’s crucial to create a balanced and thriving ecosystem within your aquarium to ensure the health and happiness of your aquatic inhabitants.

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Further Reading
Kevin Mills, the founder of Nationalparkaquarium.org

KEVIN MILLS

-- Founder --

I'm Kevin Mills, the founder of Nationalparkaquarium.org, where I share my deep passion for aquariums and aquatic life. With over 20 years of experience in fishkeeping, covering everything from tending to saltwater and freshwater tanks.

Kathleen Wood

KATHLEEN WOOD

-- Interrogator --

Kathleen Wood, a seasoned marine biologist, possesses a wealth of knowledge and experience in her field. Her research on tropical fish biodiversity spans over three decades, and she has contributed numerous scientific papers on aquatic life.