My Mossy acts the exact same way, not much phases him and when he hangs out in his water all day he soaks up a bit. When you pick him up he expels it, especially if you squeeze him at all. Mine seems perfectly fine, eats a ton and doesn't move around too much. I wouldn't be too alarmed. I haven't had him very long, about three months, but his behavior has been consistent. Someone with much more experience with mossies just joined the forum a while ago I think, maybe they could chime in?