I never believed in the "stunt growth" myth, especially since there's no scientific evidence to support the theory. Fish will grow and adapt to the size of the tank (relatively) and so will their organs. A large fish in a small tank is more likely to die from being bored and lazy then organ issues. Out growing a tank has more to do with the fish owner's personal preference and often it is based out of fear mongering than anything else. Someone sees a 1 inch oscar in a 20 gallon and they immediately cause panic and fear and tell them they need to upgrade fast or the sky will fall. As long as fish have adequate room to swim then the tank is not too small. Another myth I don't follow is the "fish grow so fast" myth. It's true some fish will grow fast, but not overnight, it can take several years. A 1 inch fish will not grow to 5 feet in 3 days or 3 months, most likely not even three years. Sometimes a fish growing fast has a lot to do with a heavy feeding schedule and a fish owner wanting to grow a mad frankenfish. Upgrading should not require any serious thought but you should only do it when you need to not when others say you should.
