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steve wrote:For shell fungus, there are two things to consider: Treatment and post treatment.

The most effective medication (it usually requires a prescription from a vet) is silver sulfadiazine (SSD) cream. Before application, the shell should be completely dry, so the turtle should be out in dry dock for an hour or more. When applying the SSD cream, you only need to use a very thin amount over the affected areas and I would leave the turtle in dry dock over night. It might still be greasy/oil in the morning, so you should carefully wipe, scrub and rinse any off of your turtle in the morning. You can then return them to the tank or leave them dry docked but repeat the treatment later in the evening. It might to take a 1-2 weeks of treatment.

Post treatment is very important because you do not want to deal with this a second time. It's possible the SSD cream won't be as effective as before (as in my case), so you would need to reply on shedding to keep the fungus controlled. Fungus is contagious to other turtles, something to consider when treating them or when one shows signs of it.