Let's keep it simple. Darwinists say that individual animals are not adaptive. PERIOD. (I know it's a silly-sounding concept, but I didn't make it up) They say that POPULATIONS adapt, not individuals. Look it up for yourself if you don't beleive me. Their version of "adaptation" is far, far different than what I described with the fish. I don't have time to educate you on it at the moment, but if you have some time, go to talkorigins.org or any other neo-darwinist website you choose and try to see if you can get an explanation for what I just described: fish -- or other animials -- quickly changing phenotypes in response to an environmental change.
(Just to save you some time, I wouldn't bother!..this is their anti-Christ!)