What does chlorine do to fish?

Okay, well, let's look at it this way. Chlorine is basically bleach. We can drink water with chlorine in it because it's in such a small, minute amount compared to our physical size, that it's not dangerous. But, if you poured, oh, let's say half a cup of bleach into a large glass of water, would you drink that? I'm thinking not. And, I'm also thinking that you wouldn't take a bath in a tub that had about a quart or two of bleach in it. You wouldn't because it is caustic and would burn your skin and throat and eat your stomach lining and you would die from lesions and internal bleeding. Smaller doses may damage and kill more slowly, but it will eventually kill.