My Kyoga flameback had not been eating for about three days. I had had him for about 4 months. He had always been reclusive, but came out to eat consistently. He never showed any signs of illness. He doubled in size in the time I had him, so he seemed healthy. A couple days ago I checked on him to see if he was coming out to eat and he was laying at the bottom of the tank, taking gasping breaths and convulsing slightly. His entire body was shivering. I immediately put him in a breeders net so the other fish would not start to nibble on him. He hung on for about another hour then had an enormous convulsion, almost like a grand mal siezure and died. He was not eaten on in any way and neither I nor my husband had noticed any other fish harrassing him. Has anyone ever seen this behavior before? Oh, and all of our water samples came out good, no other fish have been affected.