I'm guessing you are talking about a Golden Chinese Algea eater. Mine loves to eat brown algea won't touch other types. If there isn't any algea in your tank you can add aglea tabs or cucuber, or zucinnie. Mine never even noticed there were other fish in the tank untill he got big and didn't have brown algea to eat, then he started chasing the fish. Now he is in the turrtle tank on 24/7 defense, but is ating all the borwn algea in there now.
As far as one chaseing the other i would say unlikly since they are small but a little time in front of the tank watching to see what is going on is a good idea, also fun.