Can you put nail polish on your turtles shell?

Yes, putting nail-polish on your turtle's shell does not harm it, and it is actually a common practice for breeders or sellers to put a small dot of nail-polish on a turtle's shell to mark it. While a small dot of nail polish is fine, please do not consider painting more of the shell than this, as the shell could get infected because nail-polish is toxic.

Today my two sisters bought a turtle each and put them in my tank with my own turtle, Tilly, and it was hard to tell the difference between them. We researched if it was ok to put a dot of nail polish on their shell, and now our turtles are easily told apart- one purple, one orange, and one blue! I hope this helps :)