My tank is slowly being wiped out and I think it may have started with a butterfly who refused to eat and came down with a type of ich. The next day my clown died and now my royal gramma is on the way out. My scooter blenny is fine however. Let's say my fish are all wiped out. Do the parasites on the fish need another fish to survive? If there are no hosts, then the parasites die, correct? I find it odd my scooter blenny is still fine.