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.
FAQ
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.