Best Fish for a 20 Gallon Long
Best Fish for a 20 Gallon Long: Stocking Wyoming's Most Versatile Aquarium
The 20 gallon long is one of the most beloved tank sizes in the freshwater hobby — and for good reason. Its 30" x 12" x 12" footprint trades vertical height for swimming length, giving fish more horizontal room to roam and giving you more bottom space for plants, hardscape, and bottom-dwelling species.
At Tropical Treasures Wyo, we recommend the 20 long over the standard 20 high almost every time. The wider footprint provides better surface area for gas exchange, more territory for semi-aggressive fish, and a much more natural-looking aquascape, ideal for live plants and creating a balanced community tank.
Below are some of the best freshwater fish for a 20 gallon long aquarium, including active schooling fish, peaceful species, and some great centerpiece fish options.
Why 20 Long Over 20 High?
Both tanks hold the same volume of water, but the 20 gallon long's 30" x 12" footprint is dramatically better for most freshwater fish than the cramped 24" x 12" base of a 20 high.
More swimming length: Active fish like danios, rasboras, and barbs need horizontal distance to school and cruise. The extra 6 inches of length makes a real difference for fish that swim back and forth all day and display impressive schooling behavior.
More bottom real estate: Cory catfish, kuhli loaches, and other bottom dwellers care about square inches of floor space — not water column height. The 20 long offers roughly 25% more footprint than the 20 high, which benefits these ground-oriented species greatly.
Better surface area for gas exchange: A wider, shallower water column means more oxygen exchange at the surface and easier access for labyrinth fish like gouramis and bettas.
Easier aquascaping: The long, low profile mimics a natural stream bed and makes it much easier to create depth, plant carpets, and arrange driftwood compared to the tall, narrow 20 high — perfect for planted aquariums and providing hiding spots for shy or semi-aggressive fish.
🌈 1. Guppies
Guppies are colorful, active fish that are perfect for beginner 20-gallon tanks and community setups.
Why they work in a 20 gallon tank
✔ Small size
✔ Peaceful temperament
✔ Bright colors and patterns
Recommended group: 5–8 fish
🐠 2. Neon Tetras
Neon tetras are one of the most popular community fish thanks to their striking blue and red coloration and peaceful nature.
Best kept in schools
✔ Peaceful fish
✔ Beautiful schooling behavior
✔ Ideal for planted aquariums
Recommended group: 8–12 fish
🐟 3. Corydoras Catfish
Corydoras add activity to the bottom of the aquarium, making them ideal bottom dwellers that help create a balanced community tank.
Benefits
✔ Very peaceful
✔ Easy to care for
✔ Great for community tanks
Recommended group: 5–6 fish
🌿 4. Platies
Platies are hardy livebearers that adapt well to community aquariums and are known for their bright colors and energetic swimming.
Why beginners love them
✔ Easy to care for
✔ Bright colors
✔ Active swimmers
Recommended group: 4–6 fish
🐠 5. Zebra Danios
Zebra danios are extremely hardy fish and adapt well to many aquarium conditions, making them excellent active schooling fish for the 20-gallon aquarium.
Advantages
✔ Active schooling fish
✔ Very resilient
✔ Great for beginner aquariums
Recommended group: 6–8 fish
🐟 6. Honey Gourami
Honey gouramis are peaceful centerpiece fish that add personality and a splash of golden color to a 20 gallon tank.
Why they work well
✔ Calm temperament
✔ Beautiful golden coloration
✔ Compatible with many community fish
🐠 7. Cherry Barbs
Cherry barbs are colorful, peaceful fish that add movement and vivid reds to aquariums while schooling actively.
Tank benefits
✔ Active schooling fish
✔ Peaceful community species
✔ Bright red coloration
Recommended group: 6–8 fish
🐟 8. Endler Guppies
Endlers are small, vibrant livebearers closely related to guppies and loved for their bright colors and energetic nature.
Why they are great
✔ Very colorful
✔ Active swimmers
✔ Ideal for planted aquariums
🐠 9. Pygmy Corydoras
Pygmy corydoras are smaller versions of traditional cory catfish and are perfect bottom dwellers for smaller aquariums like the 20 gallon long tank, ideal for creating natural schooling groups.
Advantages
✔ Tiny size
✔ Peaceful nature
✔ Schooling behavior
Recommended group: 6–10 fish
🐟 10. Betta Fish (Community Setup)
Betta fish can work in a 20 gallon aquarium with peaceful tank mates if you provide plenty of hiding spots and plants to reduce stress.
Important considerations
✔ Avoid fin-nipping species
✔ Provide hiding spots and plants
✔ Choose calm tank mates
🧠 Tips for Stocking a 20 Gallon Tank
When stocking your 20 gallon aquarium, it’s important to avoid overcrowding by choosing peaceful species that coexist well in community tanks. Maintaining good filtration and performing regular water changes keeps the water clean and healthy for your fish.
Adding live plants can also help stabilize water parameters, provide hiding spots, and improve aquarium health by supporting natural biological filtration.
🛒 Aquarium Fish at Tropical Treasures Wyo
At Tropical Treasures Wyo, we carry a wide selection of freshwater fish ideal for peaceful community tanks, planted aquariums, and beginner setups. Our stock includes vibrant dwarf cichlids, hardy algae eaters, and colorful freshwater fish perfect for your 20 gallon long.
Visit our store in Cheyenne, Wyoming to see our current fish selection and get expert advice on building a successful aquarium with the best tank mates for your setup.
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