Aquarium Fish Compatibility Checker

Wondering what fish you can safely keep together? The DSS Aquatics Compatibility Checker takes the guesswork out of stocking your aquarium. Choose your tank size, tell us which fish you already have (or start fresh), and we’ll sort our library of 54 species with in-depth care guides into Compatible, Use with Caution, and Not Recommended — and if we don’t have verified data on a pairing, we’ll say so instead of guessing. Every verdict is computed from temperature overlap, pH, adult size, temperament, fin-nipping and predation risk, and crossbreeding (hybridization) risk, drawing on the same hands-on breeding knowledge behind every DSS Aquatics species profile. Think of it as a smart starting point, not a guarantee: individual fish have their own personalities, so always read each species’ care guide, quarantine new arrivals, and monitor new tankmates closely.

Neon Tetra (Paracheirodon innesi), a classic community aquarium fish
Photo: Cassius Chaerea via Wikimedia Commons (CC BY-SA 4.0)

1 Your tank size

2 Fish you already have

0 selected
Select your tank size and current fish, then tap Check Compatibility to see what you can keep.
Disclaimer: This checker is a planning tool — its results are estimated compatibility guidance based on typical species requirements (temperature range, pH range, adult size, temperament, fin-nipping and predation risk, and hybridization group). Estimates are not a guarantee: individual fish vary, and tank setup, stocking levels, and territory all affect outcomes. Always research each species’ full care needs before buying, quarantine new arrivals, and monitor new tankmates closely for the first 48 hours. Species marked “Insufficient Data” lack complete verified parameters — we show that honestly rather than guessing.