internal parasite

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...

I got an amazon puffer last weekend from my LFS. They are a great store (Aquarium Co-op) and they do their own quarantines w/internal parasite treatments before they put fish on the floor, especially wild caught. The puffer I got was their last one. It was pretty skinny, but active, so I went...