Planning a new freshwater aquarium or adding another fish? Use the checker to compare any two groups, or scan the full grid below. Each square shows how the fish group in that row is likely to get along with the group in that column.
Quick Compatibility Checker
Interactive Compatibility Grid
CompatibleNot CompatibleWith Caution
Hover over or tap a square to highlight its row and column, and the result appears in the checker above.
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Bringing New Fish Home
- Test your water before you shop. Make sure ammonia and nitrite read zero, nitrate is low, and pH and hardness suit the species you plan to buy. Fix any problems with a water change first.
- Float the sealed bag in your tank for 15 to 20 minutes so the water inside slowly matches your tank temperature.
- For sensitive fish, add a little tank water to the bag every few minutes to help them adjust to your pH and hardness.
- Net the fish into the tank and throw away the store water. Never pour it into your aquarium.
- Keep new fish in a separate quarantine tank for 2 to 4 weeks if you can, so diseases such as ich don't reach your main tank.
What If My Fish Are Fighting?
- Many cichlids, bettas, and barbs claim territory. Rearranging rock, wood, and plants breaks up territories so fish have to start fresh.
- Add dense plants, caves, and driftwood so shy fish have places to hide and break line of sight.
- Keep schooling fish such as tetras, barbs, and danios in groups of six or more. Small groups often turn nippy.
- Feed small portions two or three times a day so every fish gets its share.
- If the bullying continues, move the aggressive fish to another tank. Some species, especially cichlids, become more aggressive as they grow or start to breed.
This chart is a general guide. Individual fish vary in temperament, so always research a species and watch new additions closely. Tank size, stocking level, and the order you add fish can all change how they behave.