A 5 gallon tank is one of the most common aquarium sizes for beginners but it’s also one of the easiest to stock incorrectly. While a 5 gallon tank may look spacious, the limited water volume means water quality can change fast, and not every small fish is a good fit.
This guide explains which fish actually work in a 5 gallon tank, which ones don’t, and why stocking choices matter more at this size. If you’re deciding between tank sizes, you may also want to compare this setup with a fish for 3 gallon tank or a 10 gallon fish tank setup before buying fish.
What a 5 Gallon Tank Can Realistically Support
A 5 gallon aquarium is best suited for:
- one centerpiece fish, or
- a shrimp-focused setup, or
- very small fish for experienced keepers
Because the tank is small, overstocking leads to stress, poor water quality, and short fish lifespans. This guide focuses on humane, stable stocking, not on squeezing in as many fish as possible.
Best Fish for a 5 Gallon Tank
These fish are chosen because they can live comfortably in a 5 gallon aquarium when cared for properly.
Betta Fish (Best Overall Choice)
A single betta fish is the most reliable and beginner-friendly option for a 5 gallon tank.
Bettas are territorial and prefer living alone. They do well in planted tanks with gentle filtration and warm, stable water. A 5 gallon tank gives a betta enough space to swim, explore, and display natural behavior.
Best setup:
- Heated tank
- Gentle filter
- Live plants or silk plants
Learn more in the betta fish care guide or get inspiration from betta fish tank ideas.
Sparkling Gourami (For Calm, Planted Tanks)
Sparkling gouramis are tiny fish that grow just over one inch. They can work in a 5 gallon tank, but only in quiet, heavily planted setups with stable water conditions.
These fish are best for hobbyists who already understand basic tank maintenance. They prefer low flow, soft water, and dense plant cover.
Good to know:
- Keep only one or a pair
- Use a tight lid (they jump)
- Avoid loud, busy rooms
See full details in the sparkling gourami care guide and the gourami fish care guide.
Clown Killifish (Pair or Trio)
Clown killifish are surface-dwelling fish that stay small and work well in nano aquariums. They prefer calm water and do best in tanks with floating plants.
A 5 gallon tank can support:
- One pair
- Or a trio (1 male, 2 females)
Important notes:
- Tank must have a lid
- Gentle filtration is required
Read the full clown killifish care guide before choosing this species.
Chili Rasbora (Advanced Nano Option)
Chili rasboras are beautiful but delicate fish. While they are often listed for small tanks, they are not beginner-friendly.
They only work in:
- Fully cycled tanks
- Heavily planted setups
- Stable water conditions
If attempted, keep expectations realistic and avoid overstocking. Learn more in the chili rasbora care guide.
Can You Keep Shrimp in a 5 Gallon Tank?
Yes, and in many cases, shrimp are a better choice than fish for a 5 gallon aquarium.
Shrimp produce less waste and thrive in planted tanks. Popular options include:
Shrimp-only tanks are easier to keep stable and offer constant activity without stressing fish.
Helpful resources:
Fish You Should NOT Keep in a 5 Gallon Tank
Many fish are commonly recommended for small tanks but should not be kept in a 5 gallon aquarium.
Guppies
Guppies breed quickly and produce more waste than expected. A small tank becomes overcrowded fast. See guppy fish care for better tank size options.
Neon Tetras
Neon tetras are schooling fish and need larger groups and more swimming space.
Goldfish
Goldfish grow large and produce heavy waste. Even one goldfish is unsuitable.
Corydoras Catfish
Corydoras need groups and floor space, which a 5 gallon tank cannot provide.
How Many Fish Can You Put in a 5 Gallon Tank?
Avoid rules like “one inch of fish per gallon.” That guideline doesn’t work for small tanks.
Safe stocking options:
- 1 betta fish
- Shrimp-only setup
- 1–3 nano fish (experienced keepers only)
If you want more fish, upgrading to a larger tank is the better choice.
Planted vs Bare 5 Gallon Tanks
A planted tank is far more stable than a bare setup.
Benefits of plants:
- Improve water quality
- Reduce stress
- Provide hiding spots
Beginner-friendly choices include low light aquarium plants and floating plants that soften lighting and calm fish.
5 Gallon Tank Setup Tips
To keep fish healthy:
- Use a gentle filter
- Always use a heater for tropical fish
- Perform small, regular water changes
- Avoid sudden stocking changes
If you’re starting from scratch, follow a freshwater aquarium setup guide to avoid common mistakes.
5 Gallon vs 3 Gallon vs 10 Gallon Tanks
Understanding size differences helps prevent stocking errors.
- 3 gallon tanks: Best for shrimp or snails only
- 5 gallon tanks: One fish or shrimp focus
- 10 gallon tanks: Much more flexible and forgiving
Compare with:
- fish for 3 gallon tank
- fish for 10 gallon tank
If you’re unsure, bigger tanks are always easier to maintain.
Final Thoughts
A 5 gallon tank can be a great aquarium when stocked responsibly. The key is choosing fish that match the tank size not forcing the tank to fit the fish.
If you want simplicity, a single betta or a shrimp setup is the safest choice. If you want variety, consider upgrading to a larger tank before adding more fish.
Use this guide as a reference, and always research individual species before buying.
