My ID use to get a fat lip from banging into the glass. He is in plastic pond now, no more bruises. I always use salt whenever my ID's get anything. Do a water change, add salt 1 TBS per 5 gal and raise the temp just a bit. I have had my big one (30") for over 17 years and salt has cured many cases of ick, cuts from fights, and any fin damage. Please make sure you tank is wide. They need room to turn. I feed algae pellets and massivore, every other day. They all hand feed, even the TSN who charges the top of the water when its his turn. Enjoy.