Mud and musk turtles do not require the UV light that other turtles need and are not aggressive at all. I think that it will do just fine in that tank but I would recommend that you make sure he cant crawl out of it and that you add some more furniture for him to climb on and rest to breath. Tall plants or floating plants do this job really well but he will eat away at those so I would suggest finding some fake water lettuce or something.