Bill, I talked to a local catfishing operation where people fish for catfish and pay by the pound. He also sells stocker fish and furnishes a lot of tilapia to local eateries. He says he uses a lot of salt in his ponds. He says it cuts down on diseases. I don't recall how much he uses but remember that it sounded like an awful lot. As he put it, one sick ten pounder costs him a lot of money. Then, when he has tilapia illnesses, it can really hurt.