Hi i had a a cutllefish a few months a go in a net breeder but somehow it escaped and attacked my cowfish. The cowfish released its toxins and wiped everything in the tank. Do cowfish have copper in their toxin. One more question is i;m thinking of getting a larger tanks and was wondering is all you use inn a ceph tank Reverse osmosis water. The smaller tank that i had i used nutri seawater and RO top off. Do you use RO water to mix the salt too.