The Kribs seem to do ok, they are definately the bosses of the tank, but none of my fish have ever had picked fins at all. They each have their end of the tank, and when the other Krib ventures too near they will chase it off. Other than that they leave the other fish alone except for the penguin tetras and the oto's which they don't like to have hanging out in their "spot", for some reason its just the those 2 though, maybe the black line down their sides makes them look like a Krib to the 2 Kribs? Oh yeah, they seem to have a taste for Hygrophilia, which they have trimmed all the leaves off of the tops.....