I am trying to diagnose my catfish, he is getting these large sores on his belly and sides, the one on his belly closer to his mouth is ketting pretty deep. He is now also getting some bubbles in his skin and his head is starting to get so you can see his skull. I am thinking about putting him out of his misery, he doesnt look like he is going to make it. I have been treating my tank with melafix because I have some scaleless fish and I dont want to harm them while trying to heal my one cat.