ok so this is the 2nd time i have seen a death like this. I had channel catfish basically seizure to death and now i have lost a fire eel and it is doing the same thing. It just looks like its having a seizure. It was swimming out of control and flipped over. The same thing happend to the catfish. Could this be some type of internal parasite? theres no visible signs externally on the fish no fungus or anything that looks abnormal. They were both in a 120g tank. the catfish was 4'' and the eel was about 7''-8''.