How Many Fish in a 5 Gallon Tank?
There's no single magic number, a 5-gallon tank can hold a big school of small fish or just a couple of large, messy ones. What matters is each species' adult size, bioload, schooling needs, and temperament. The calculator below is pre-set to 5 gallons; add the fish you're considering and it'll flag any problems.
Example 5-gallon stocking ideas
- Betta tank: 1 male betta + 1 nerite snail (+ a few cherry shrimp if peaceful).
- Nano shrimp tank: a colony of cherry shrimp + a nerite snail.
- Nano school: 8–10 chili rasboras (lightly stocked).
Always cycle the tank first, add fish gradually, and keep up with weekly water changes. These are starting points, run your exact list through the calculator above.
Fish featured in these 5-gallon setups
Photos via Wikimedia Commons under their respective licenses, click a credit for the source.