My Betta, Captain Jack, seems to sleep at the bottom of his tank, often in a corner or wrapped around one of my aquarium plants. Is this normal, or could he be sick? When I turn the light on he starts swimming around again, so he's not getting caught or stuck as far as I can tell... It's my first time with a tank, and I want to be sure that he's healthy and happy in there. During the day and when the light is on, he's pretty active in swimming around, and he goes crazy when I open the lid to feed him, so he doesn't seem sick... Thoughts?