Yellow Tang with tattered dorsal fin

Hi All, I have a 135 gallon educational tank in a middle school and the yellow tang has a tattered or eroded dorsal fin. I'm feeding high quality food, including algae sheets (which I don't think it touches honestly). It's eating well otherwise and on average only one fish seems to be even a bit aggressive towards it (dwarf anglefish), but I'm not there all the time. I have 3 basslets, a saddleback puffer, 3 monos, 2 clownfish, a couple of small blue yellow tail damsels, a blue tang and a red strip dwarf anglefish. If I don't see aggression, options on switching up food perhaps? The other fish are very healthy and active.