One dead fish a day HELP

[Tarolisol]

Yeah i never had a problem with the toxin i was always worried when he was sick but never seemed to bug anything. When he got it i removed all my fish and quaritined. All but the clowns but they never got a touch of velvet. I think there super fish. Thats not even as bad as it got it go to a point i thought there was no way the fish would live, its skin was falling off you could see the flesh peel. But he came through.