Dog-toothed characin, Hydrolycus armatus
Just in case you thought it's only marine fish that have beauty issues here's a stunner from freshwater. In the family Cynodontidae, or Dog-toothed characins they have a problem with teeth it seems. The problem appears to be they borrowed them from a sabre-toothed tiger, and despite the fact they don't really fit, and they haven't given them back.