Sometime over the weekend, my chocolate chip star started looking like this (http://tinypic.com/r/2moov7o/9). I talked to my lfs, and they said to do some iodine soaks and see if that stops the spread. I do not want to medicate the tank since they're so sensitive. The only other thing in my tank are 2 very small damsels and a couple live rocks. All ammonia, nitrite, nitrate, specific gravity, and temperature levels are fine. Any suggestions as to what could be causing this? I don't want to add anything else to the tank until I know the cause, but I'm not sure if I should pull the star so it doesn't foul the whole tank