Fish Compatibility Checker
Check whether two species can safely share a tank.
How it works
Compatibility considers temperament, adult size, water parameters (temperature, pH, hardness), activity level and diet. Species are compatible when their parameter ranges overlap and neither will bully, eat or outcompete the other.
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Formula & Method
Compatibility considers temperament, adult size, water parameters (temperature, pH, hardness), activity level and diet. Species are compatible when their parameter ranges overlap and neither will bully, eat or outcompete the other.
Example Calculation
Neon tetras + bettas: borderline. They share temperature/pH, but a nippy betta or a tetra nipping betta fins can fail. Neon tetras + corydoras: fully compatible.
Frequently Asked Questions
What makes fish incompatible?
Mismatched water needs, large size differences (predation), aggression, fin-nipping, or very different activity levels.
Can I mix any fish if the tank is big enough?
Size helps but doesn't override predator-prey or parameter conflicts. Always match needs and temperament.