I bought a male banana ball python from a reptile expo in Denver, CO. When I got him on 8/18/2015, he was 99.2grams (3.5oz). In that entire time, I have only gotten him to feed around 5 times, and he has put on 5.6grams (.2oz). He now ways 3.7oz. I have tried live rats, f/t mice and rats, different sized prey, a different tub, different lighting, feeding him at night, feeding him during the day, warming him up before hand, adjusting his enclosure temperature/humidity and changing substrate. He hasn't eaten in two weeks, and he's half the size (at least) that he should be. I have gotten him to strike at prey, but when he misses, he gives up.

I'm at a loss for what to do because, while he is still active, and still sheds, he isn't gaining weight. Nothing about him is abnormal except his appetite.