A tang. Any tang, for that matter. I saw them in the wild, will see more this year and I understand now they don't belong to anything but the largest aquariums. I have the one of the smallest surgeonfishes- Kole tang, in my 100g and if I could rethink my decision, I would never have brought it home. They really need a lot of space and they are such an important fish on the reef. It's doing great in my tank, but I still feel sorry I can't give him more space to explore.Well, lesson learned.
i would have to agree!