I read that but don't you just dump their dirty water out on the ground? it also tells you on the bottle how to use it to disinfect water storage systems, If your going to pour the water into the pond or river then i would say don't use it. But pouring it on dry ground isn't going to hurt the fish. or putting it down sinks [drains] which i don't do either.if you have a septic system that shouldn't be going into a river or pond or lake NOW that will hurt the fish.there is a disposal warning not to dump effluent containing oxine into water or down drains due to fish toxicity