I'm very cautious about my puffer fish, because of his very sharp teeth and the potential to do damage to my fingers. I never really worried about any other fish. In the fresh water tank I've had the mollies pick on my hand, but that was more like eating dead skin (yes, I know, gross). today while I was feeding the anemones in the 20 gallon tank one of the skunk clown fish attacked my hand. It actually hurt and very much startled me. If course it didn't do any damage, because, unlike the puffer, the clown doesn't have sharp teeth, but they do have a bony structure, like flattened teeth, in their mouth that can hold onto prey or pinch a person's arm pretty good.