I have two Black Moor goldfish in my tank. Both were bought at the same time out of the same tank, but one fish has a tail that is connected at the top, and the other has one that isn't. So one fish has a tail that looks like a triangle missing the 3rd side, and the other looks like he has two tails. 
Does anyone know why this is?
-Matt
Does anyone know why this is?
-Matt