The fish I regretted getting was a small school (4) of Chinese algae eaters when I first started and before I knew any better. They were great as juveniles but as they grew they got very aggressive. I gave the largest female to my uncle which is doing very well in his 85g octagon with his parrot fish, I sold two to a fish shop and the remaining male I still have believe it or not... He is a much better fish with out the school but if I had it to do over I would have gotten Siamese algae eaters instead.