I'd contact the water department and get a report of what they do to their water--they should be able to provide such a report to you without any problem. My water dept. started adding chloramines to the water which Amquel+, Prime and some other high quality conditioners are supposed to handle just fine but don't (or perhaps there's other stuff in my water that now with the added chems have a negative affect on living critters). If your water dept is only adding chlorine, it's not such a big problem since chlorine will dissipate from water within a day or two and any good dechlorinator (not Stresscoat) will undo chlorine fairly fast. I sterilize tanks and other used fish equipment with Clorox and then so a soak overnight in dechlorinator (triple strength) treated water and have had no problem. Signs that your fish are reacting badly would obviously be if your fish, after a water change, start acting oddly, swimming oddly, try to jump out of the tank, start gasping at the surface, keel over, etc. If you see any of that going on, immediately net them out and put them into some spring water until you can figure out what to do about the tap water. My tap water, even after using Amquel+ which is supposed to dechloraminate water, kills fish, snails, and even aquatic plants so I had to switch to bottle spring water. After you do a cleaning and replace the water, just keep an eye on your fish, they'll let you know within an hour or so if things are good with them.
