Turtles with shell cracks or shell rot are usually dry docked. I place shell rot cases in water for four hours each day to feed and potty, then dry dock them in a soft towel with a tiny, shallow water bowl for the rest of the day. This helps keep algae from growing on them. If your turtle has shell rot but is still swimming around outside its tank, put him in a larger container with an amount of water equal to about one-third of his total volume. Let him stay in this new environment for about half of his normal swimming time. If he seems better after two days in this new situation, it was probably just a cold. If not, take him to a veterinarian right away so that he does not suffer any more damage from the infection. Treatment for shell rot should only be done by a veterinarian. There are several different types of bacteria that can cause this disease, so antibiotics will not work against it. However, if left untreated, shell rot can lead to myiasis (fly infestation), which is much worse for your turtle. Therefore, treatment is necessary for preventing further illness and damage to your pet. Shell rot is easy to diagnose. You should call your vet right away if you find evidence of the problem in your turtle. She or he will be able to tell you how to proceed from there.