How the grade works
Every fish in the checker comes from the public Species Ledger: adult size, temperature and pH ranges, temperament, schooling needs and known problems like fin nipping, each checked against at least two care sources and dated. The checker compares every pair of fish, checks each one against your tank size, and adds up the bioload. Serious problems (one fish eating another, no shared temperature, aggressive fish with peaceful ones) cap the grade at D. Full rules.
It’s a cautious community guideline, not a guarantee. Individual fish vary, and a good local fish store knows your water. If you think a rule is wrong, tell us: we fix it and log the change.
Popular compatibility checks
- Betta (male) + Neon tetraUsually OK, with care
- Betta (male) + GuppyCompatible
- Betta (male) + Cardinal tetraUsually OK, with care
- Guppy + Neon tetraCompatible
- Betta (male) + PlatyCompatible
- Cardinal tetra + Neon tetraCompatible
- Betta (male) + MollyCompatible
- Neon tetra + PlatyCompatible
- Cardinal tetra + GuppyUsually OK, with care
- Betta (male) + Zebra danioRisky
- Molly + Neon tetraCompatible
- Guppy + PlatyCompatible