White Growth on Fish...

Not good, not good at all. The white growth is not just on the aquarium sides anymore. Now it can be found on the clown loaches also. At least, the stuff is visible on the sides of the clown loaches. The second clown loach that I purchased from Lang's seems to be affected more than the first. But they are both *scratching* against the bottom of the tank. I plan to call Drs. Foster Smith to find out what the growth could be (since it is obviously not an algae!) and what I can do (medicate?) to take care of the fish and the tank.