After I placed my senegal in my new 422 4-side black tank, it started behaving abnormally. Initially, it was roaming about in it's new tank but then it started pressing his nose against the glass. When I placed a huge black cardboard against the transparent glass, it settled down. That's when things started to get strange. It started shaking its head, once in a while. Although it seems to behave regularly, I'm afraid that putting my other bichirs in the tank might trigger such behavior in them as well. Can anyone help?