The fish compatibility checker helps you build a peaceful community aquarium by checking temperament, size, and water parameter compatibility between common freshwater fish species.
Check Fish Compatibility
Building a Community Aquarium
A well-planned community aquarium uses all levels of the water column: surface fish, mid-water swimmers, and bottom dwellers. This natural zoning reduces territorial conflict and maximizes the use of tank space.
Peaceful Community Starter Tank
An excellent beginner community: 6 neon tetras (mid-water schooling), 6 corydoras catfish (peaceful bottom dwellers), 6 ember tetras or celestial pearl danios, and 1-2 nerite snails. This combination is peaceful, works in 20+ gallons, and keeps the entire water column active.
Frequently Asked Questions
Is this fish compatibility checker free?
Yes, completely free with no signup required.
What makes freshwater fish compatible?
Fish compatibility depends on: (1) Temperament — peaceful fish should not be kept with aggressive species. (2) Size — large fish may eat small fish. (3) Water parameters — pH, hardness, and temperature ranges should overlap. (4) Space requirements — bottom dwellers, mid-water, and surface fish can share a tank by occupying different levels.
Can I keep bettas with other fish?
Male bettas cannot be kept with other male bettas (they will fight). Males can sometimes be kept with peaceful, fast-swimming species that do not have flowing fins (which trigger aggression). Good tankmates: corydoras, snails, mystery snails, short-finned tetras in large enough tanks. Avoid fin-nipping species (tiger barbs, serpae tetras).
What are good beginner community fish?
Excellent beginner community fish: Neon tetras (peaceful, school of 6+), Guppies (peaceful, easy to breed), Corydoras catfish (peaceful bottom dwellers), Platies and Mollies (peaceful livebearers), Zebra danios (peaceful, hardy), Cherry barbs (generally peaceful). Avoid: Cichlids, oscars, and jack dempsey for community tanks — they are too aggressive.
Do fish need to be in schools?
Many species are shoaling fish that need company of their own kind: tetras, barbs, danios, corydoras, and rasboras all do significantly better in groups of 6 or more. Solo shoaling fish are often stressed, develop aggression, or lose color. Solitary species like bettas and most cichlids should not be grouped.