Well, I did a little reading on chlorine toxicity. It apparently depends on a lot of factors, including pH, heavy metals in the water and oxygen available. There weren't any definite figures on pH. If he got the full measure of chlorine in his gills, that is at toxic levels, but if the rest of the water is OK, he has a chance. Trembling and discoloration are signs of chlorine poisoning. Make sure you have the tank well covered, as chlorine poisoning can make their escape bahaviours kick in.
I would suggest you add an airstone to the tank, if you don't already have one, as oxygen available can help if his gill function is reduced.
Good luck with him.