I have a ~5 inch long RES named Franklin. Normally he is a hungry little bugger. Every morning when I wake up, he's already up and frantically splashing and swimming against the side of the tank to get my attention. As soon as he sees the food can, he gets into a frenzy. He instantly gobbles up all pellets placed in his tank. Even less favorable foods like lettuce are attacked immediately, even if he sometimes leaves some for later. He has active periods and lethargic periods where he just sleeps all day, but food always gets his immediate attention no matter what kind of period he's in.
I was away on Sunday which was his off day, and he was asleep when I got back so I just let him be. Monday, feeding day, came, and I woke to find him chilling on his dock - not asleep, just sitting there looking around. That was weird enough, but then I had actual reason to be concerned when I waved the can of food in his face and he was completely un-phased. Nothing I tried got him off his dock (well I didn't try anything mean like shaking the tank or whatever, but no amount of luring or coaxing did anything). When I got near him, he just pulled his head into his shell.
This was only the first day he refused food, and I had to go to work, so I let him be. I came back from work and found him still on his dock, and it looked like all or most of the food pellets had just gotten bloated and sunk to the floor. There was also turtle stool on the floor of the tank, which was another bad sign as it's super rare I even see his stool since he normally immediately recycles it (which is kind of gross, but I accept as normal turtle behavior).
Now very concerned, I did a thorough checkup. Making him very angry, I reached in and picked him up to give him a look-over. His shell didn't seem to have any soft spots or oddities, and I couldn't find any blemishes on his skin. His eyes look normal, and I don't see any discharge or anything around his mouth or other orifices. His breathing seemed normal as well - no wheezing or other troubles breathing. The water temp was at a balmy 77-79 degrees. The water was a little murky, plus there was new stool and pellets littering the bottom, so I decided to give him a cleaning. This made him mad as well, and he frantically moved around the tank (first swimming, then walking when the water level got low enough). This at least restored my confidence that he was able to be active - I didn't observe any oddities in his swimming or walking.
I let him sleep under his dock pretty much all night (not too unusual for Franklin) and decided to try feeding again in the morning. He was on his dock again, just like yesterday. His limbs were all out, his neck craned towards the heating lamp a bit, and even his tail was sticking straight out - so he didn't seem to be afraid or stressed or anything. Seeing me didn't cause him to leave his dock like it normally would at feeding time - no begging or anything. After a few minutes, he slid off the dock and started swimming around, but still no begging. There was more stool on the bottom, and he sniffed it a couple times, but immediately moved on each time. I took out the food can and started shaking, and he followed it around the tank a little, though much much slower than normal, but did not even investigate the pellets when they were placed in the tank.
At the moment he's just getting on and off his dock. He'll go sit there for a few minutes, plop back into the water very briefly, then go climb right back up on the dock. I've listed my results of checking for all the symptoms I know to check, but I've run out of ideas. Does anyone have any idea what could be wrong, or what I should try next?
