How Many Fish in a 100 Gallon Tank?
There's no single magic number, a 100-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 100 gallons; add the fish you're considering and it'll flag any problems.
Example 100-gallon stocking ideas
- Community showcase: large schools of rainbowfish and cardinal tetras + a dozen corydoras + a pair of pearl gouramis + bristlenose pleco.
- Goldfish tank: 3-4 fancy goldfish, or 2 common goldfish (coldwater; ideally a pond for commons long-term).
- Cichlid centerpiece: an angelfish group + big tetra schools + kribensis pair on the bottom.
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.