I found my pleco dead today. He was by himself, and was found with his head and tail shredded, and a hole in his stomach, like something came out or went inside him, and there was what looked a little like a bit of poop coming out of his bottom. Unfortunately I don't have a picture, but he has had a red spot in the area since he was a baby, though he never grew much, and rarely ate. Although he was never in discomfort, he'd end up hiding when someone would get close to him or accidentally bump the tank. I think I've had him for two years, and he never seemed unhealthy, in fact he was swimming around yesterday. Normally I'd say a fish attacked him, or he got caught in something, except he was alone in the tank, and there was nothing he could've gotten caught on or hooked on in the tank, and no signs he was struggling anywhere. I'm unsure what to do with the tank now, because I don't know if it would be safe to put my hands in the water to clean or move things around, in case there is a parasite/parasites in the water. Any help in solving this mystery is appreciated If it helps, the tank he was in is 40 gallons, it has a castle, fake plants, and cichlid rocks in it, a heater, and a good filter that was small enough he couldn't get inside, and it had plenty of algae for him since he wasn't eating much, though I did try to keep it clean without stressing him too much, and he also used to be given pleco wafers, but I stopped putting them in because it was making the algae worse. Oh, and he was bough at PetSmart.