Originally I had only 2 rainbow fish in my 90 gallon tank one I believe is a mccullochs rainbow and the other a turqouise rainbow ( don't know scientific names) I bought 6 more mccullochs and all of the sudden the turquiose was chasing the other new smaller rainbow fish which wasn't that uncommon but it also chased the slightly larger original mccullochs rainbow. during this though the turquiose whould display a very bright yellow stripe down its back. it is normally a bluish and gray. which would almost dissappear when it stopped chasing them. this drastic color change amazed me. this only lasted for maybe the first few hours and now they all don't bother each other. has anyone else ever witnessed this kind of color change.