I'm not sure. He had seemed mopey, almost as though he were depressed. A couple of hours ago, he became lethargic though he ate. I cupped him in water from an established tank so I could clean his hospital tank thoroughly as I was worried after losing the salamander girl. When I went to move him back to his tank, I noticed he had stopped moving. I'm not sure what had happened. I quadruple checked to make sure he had passed before telling Devon. I have triple checked the rest of the fish to make sure no one else is acting strangely. So far, all the rest are behaving normally.