What a community tank is
A community aquarium houses several different species that coexist peacefully. It is the most popular kind of freshwater tank for good reason — done well, it is lively, varied and endlessly watchable. The catch is that "peaceful" is not the default. A stable community depends on deliberate planning around three things: compatible water parameters, compatible temperaments, and sensible use of the tank's swimming levels. Get those right and the tank largely runs itself.
Start with the tank and the cycle
Before choosing fish, get the tank itself ready. A larger volume gives you more stocking options and more stability, so pick the biggest sensible size from the aquariums hub, and set it up following our tank set-up guide. You will need a filter and, for tropical fish, a heater.
Then cycle the tank fully before adding livestock. A community tank only works if the biology is stable first — everything below assumes you are stocking a cycled, settled aquarium.
Match parameters and temperament
The most common beginner mistake is choosing fish by looks alone. Instead, group species that want the same environment and behave in compatible ways.
- Water parameters: keep fish with similar temperature, pH and hardness preferences together. See tropical temperature ranges as a starting point.
- Temperament: avoid mixing timid species with boisterous or fin-nipping ones. A peaceful shoal is easily bullied by a single aggressive tankmate.
- Adult size: a fish small enough to fit in another's mouth eventually will. Match sizes sensibly.
Stock across the tank's levels
Fish naturally occupy different zones, and a good community uses all of them so the tank looks full without crowding any one area. A classic, beginner-friendly structure is a shoal in the middle, a calm centrepiece, and a cleanup crew along the bottom.
- Mid-water shoals: neon tetras, harlequin rasboras or ember tetras, kept in groups of six or more.
- Centrepiece fish: a peaceful focal species such as a honey gourami or dwarf gourami.
- Bottom-dwellers: a group of corydoras or an Otocinclus clean-up crew.
- Invertebrates: Amano shrimp or cherry shrimp, if tankmates are small and peaceful.
Add fish gradually
Even in a cycled tank, adding everything at once can trigger an ammonia spike and cause aggression as territories are established all together. Stock in stages over several weeks, ideally starting with the calmest species, and acclimatise each batch slowly. Quarantining new arrivals first is wise. Once stocked, a steady routine of water changes and light feeding keeps the whole community stable — the maintenance hub has the full rhythm.