The neons aren't nippy at all, it's actually one of the other mollies that's being nippy. I think that he might have had his fins folded in, do they do that when they feel scared or threatened or something? The alpha-male Molly likes to attack the others during feeding time so maybe he was just...
Please help, I think something is wrong with one of my mollies. It swims around in the same spot and has some damage to its fins. It's tail fin is missing the top and bottom parts of its tail, so the top and bottom edges of the tail are basically parallel to her belly. She doesn't have fins left...