My 5 in. senegal does the exact same thing. Sometimes he's at the top and sometimes he's at the bottom. When I got him it was pretty hard to find something that he would eat. I tried ciclid pellets, fish flakes, and even reptomin pellets. Then I decided to try a cricket. I threw it in and 10 seconds later, my bichir swam up and grabbed it. He ate two that day. So I would recommend giving him a cricket to see if he would eat.