all my turtles have this brown tannish looking stuff on the tail end of there of all there shells and my biggest one has it all over its bellly. 2 RES 1 YBS...in the water its not as bad as out of the water i dont know the cause of it but i have pictures any ideas would be great...what im talking about is outlined in red square
Its not deadly but it can cause related issues that can be serious. The most effective treatment is silver sulfadiazine cream, which you will need to get from a vet.