Is my clown loach sick?

[thetexasranger]

I've had this guy about a year. I noticed he became withdrawn maybe 3 weeks ago. He still loves to eat but he seems pale (particularly on his abdomen) and just a lot more shy than usual during the day. No white spots and none of my other fish have anything going on. I've read it could be skinny disease but I'm thinking it COULD BE a lot of things...I've never had any parasites in the tank and I haven't added a fish or plant in several months. Here's some photos (always the one in the foreground) though I'm not sure they're all that helpful.

 

[lauraf]

He doesn't look that well in your pics. "Skinny disease" is not one illness - it's a catch-all name covering a few symptoms, which can be caused by different things, like parasites, as you mention. How are your water parameters?