Good article on it from Angelsplus:
http://www.angelsplus.com/ArticleChloramine.htm[\QUOTE]
The recommended experiment in the article is too complicated, and it is too risky to experiment on your priceless fish.
A much simpler experiment is to run a bioassay test on your disposable fish in a separate tank. Here is what I did in my former residence when the water treatment was switched to chloramine. I threw in a few surplus fry into an established 10 gal tank, did variable amount of water change, added variable dosage of dechlor and refilled directly with tap water to see if the fry survived. What I found is that my fry survived indefinitely with as much as 99% WC with the recommended dosage of dechlor. But if I used no dechlor or underdosage, the fry will die in 5 min. Using fry for experiment is best because they are the most sensitive population so if they survive, adult fish will. The dechlor I used was API Tap Water Conditioner that contains sodium thiosulfate only, proving that I don't need to neutralize the residual ammonia. Since your situation may be different, you may want to run your own experiment.