You sure it's a mud turtle? Every discription I have ever read describe this exactly. The yellow stripes from the eyes down the head, the shell, everything.. I'm sure the environment would be fine. It probably would have got ate by those huge Gar that were roaming the waters where I found him. There were tons of turtles in there, cooters and the like. This one was just right by the land. I know they need shallow waters and a dry basking area. I already have his cage made up. It has silica sand for the flooring and shallow water. Here is a picture.
Also, does it take awhile for them to be able to close their shell?
P.S. I've kepy Yellow muds before, so I'm aware of what they need.