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.