I agree to treat the whole tank or you will be just delaying another round with the rest of your fish. It is not just the fish that have Ick, the whole tank has it. If it really is Ick... are the white spots tiny like a grain of salt or ar they bigger?? Are they fluffy looking like cotton?? If it is Ick, once they drop off your fish and get to your gravel they will multiply and then find more hosts. Also, the faster you address the issue the better chance your fish have at not just surviving, but also getting a secondary infection as well. Everytime the parasite drops off your fish it leaves an open wound for other infections to set in. I always use salt and crank up the temp to 86-88 for a couple weeks, however Quickcure works well too, however the carbon needs to come out if you use it and also many fish don't take too well to the chemicals... like loaches and what not. Anyway, good luck.
