My FRT developed a few small white spots on its shell, and I cant really tell if its fungus or he just hit somthing in the tank, but I took him out, let his shell dry and put iodine on a paper towel and rubbed the spots lightly.(When out of the tank the spots are invisible). Anything else I should do? What brand of salt should i add to the aquarium and how much per 10 gallons? Thanks.