well, I cannot really see it from the photo, but it sounds like Ick (the white spots are the parasites moving to the stage where they broadcast spread eggs in the tank).
The best method is copper (opinion), however, you need to be very careful with it, as too much is toxic, follow the directions closely and buy a copper test kit to monitor daily (both copper and test kits are cheap for this). Some suggest garlic laden foods and hypo-salinity (I think its like 1.010 ish - 1.007 ish specific gravity), however, there is no verified method except for copper from veterinarians (I've spoke to and read from). There are some new foods from Dr. G's for parasites and worms, but I haven't tried them so I won't recommend them, but worth mentioning.
This disease persists in fish in the wild, but is brought on by the fish having stress during collection, shipping, and then moving to your tank. The fishes natural immune system usually will keep this in check however, with the conditions listed above, creates an immune system drop in effectiveness (from what I understand).
This is why quarantine is necessary with all livestock we put in our tanks prior to introduction into our display tanks (Corals and fish). The only sure-fire way to remove ALL your fish and put them in a holding tank and treat them accordingly. Then let your tank run devoid of fish for 8 -12 weeks to kill off the free living parasites in your display. Then re-introduce them into the tank and you should be good.
However, do not add copper to your tank with inverts and corals or they all will die, Copper will often be attached to gravel, silicone, and live rock so do not do it! Unless you have a f.o.w.l.e.r, then its up to you.
