Hey, forum! Today I took a red ear slider from some people who no longer wanted him. They cared about him, but didn't have him in great conditions. He's been kept in a baby pool with a basking log during warm days outside and nights in a 20 gallon with only water and gravel. He's about 7 inches from one end of the shell to the other so a 20 gallon was clearly too small. During cold months (which lasts a few months per year here), he was kept in the 20 gallon 100% of the time. He had no UVB nor basking lamp at this time.
So do you think those discolored spots on his shell are normal or he has some sort of shell rot or other issue going on? They said he's going through shed right now, not sure if that's related. A couple scutes have already come off.

