Check which fish can live together in your aquarium.
Select the species you want to keep and find out if they’re compatible with each other: temperament, size, temperature and water needs. No sign-up, no data stored.
Aquarium Fish Compatibility Checker
Based on Real Species Profiles
We compare temperament, adult size and water parameters for each species.
Detects Common Conflicts
Flags problematic combinations: territorial fish, predators or water incompatibilities.
Instant Result
Select your fish and get the compatibility result instantly.
No Sign-Up, No Waiting
The calculation happens in your browser. No accounts or passwords.
Not all fish get along.
Mixing species without checking their compatibility first is one of the most common causes of stress, fighting and deaths in a community aquarium. Even if two fish seem calm at the store, their temperature, pH or space needs can be very different, or one may turn out to be territorial or predatory as it grows. Checking beforehand avoids most of these problems.
What result do you get?
Before buying a new fish:
Check whether it will fit in with the fish you already have.
When setting up a community tank:
Plan from scratch which species you can safely combine.
If you change species:
Verify whether the new species is compatible with the ones already living in your tank.
Frequently Asked Questions (FAQ)
Do I need to create an account?
No, never. You can use the checker directly, with no sign-up or passwords.
What happens if two fish are incompatible?
The checker tells you the reason for the conflict (temperament, size, temperature or pH) so you can decide whether to look for another combination or adjust your tank.
Is the result saved if I close the tab?
No. The calculation happens in your browser and disappears when you close or reload the page. If you want to keep it, you can write it down or take a screenshot.
Does this checker replace a specialist’s advice?
No. It only gives general guidance based on species profiles. For specific questions about your tank, consult a specialized store or an aquatic veterinarian.