Recently I've run into a problem with my Senegal. He's nice and active, and used to eat like a pig, but now it seems he is either regurgitating or just not swallowing food. I used to feed him by dropping food right near his head which he ate off the surface. However now he is usually at the bottom of the tank, and hardly frequents the top like he used to. He still eats/tries to eat his pellets (Hikari sinking Carnivore Pellets) but they begin to absorb water and become soggy, so he bites them, or even tries to eat them whole like he used to, but the food just seems to sit in his mouth. He proceeds to spits pieces out, they just dirty the tank, and it doesn't seem like he's eating more than half of the pellet. Any suggestions?