How big is your turtle? ~5 inches
How long have you had it? 6 months
What is the water temperature? Room temp (~75F)
Did you use a thermometer? No
Are you using a water heater? No
How much water is in there? ~6 gal
Are you using a water conditioner? no
Are you using any filtration? Yes (not sure of the brand, but it cleans up well)
What is the basking temperature? ~90F
Is there a basking light? Yes
Is there a basking platform that is easy to climb on? Yes
What kind is it or what is it made out of? Smooth rock for climbing out which leads to smooth plastic for basking
Is there a UVB light? not sure, but pretty sure no (my mom bought everything and set it up)
What have you been trying to feed it? Turtle pellets and lettuce with the occasional green beans and carrots
When was the last time your turtle ate? yesterday
How big is the tank/pond/enclosure? submerged part ~3 ft x 2 ft, dry part ~2 ft x 1.5 ft
Is the tank near a window? yes
Is the tank in a room with a lot of activity? No (just occasional walkthroughs 3-4x daily)
Have you read the Basic Care section? yes
Have you searched the forums for similar situations? yes
Is there any other unusual activity/symptoms? No, but my other turtle is fine as of right now
One of the scutes just all of a sudden up and peeled clear off the shell tonight. There was no real warning about this happening, he was fine about 6 hours earlier. The area under where the scute was is whitish and there is a bit of brown next to it.
The first turtle is the one that has the shell issue (Kreacher), the other one is the one that is currently ok (Winky).
Now that I am looking at Kreacher (especially from the underside), he doesn't look so good. I hadn't noticed the fungus like growth on his underside because he was behaving normally (and still does) with the exception of his shell peeling apart. The chipping on the edge of his shell was there when we bought him and so was the small chink on the top side in the bottom parts of the pictures. I'm thinking some kind of shell rot is going on. What can I do to try and help him out?
Winky still looks as she did the day we got her (she is ~4 inches). I would like to keep her that way.

