Hello,
It looks like your lighting is good, as well as the supplementation schedule too. His physical condition
appears fine, to me. He doesn't look ill, & his eyes look alert. He has a very sweet face.
It is a possibilty he might be going into a slowdown phase, or brumation. It sounds odd but sometimes
they do go into brumation in spring & summertime though it might not be a long phase.
As long as he isn't losing weight, I wouldn't worry too much. You could get a fecal done, just to be sure
there isn't anything else going on with him to cause a loss of appetite.
Tracie