Whenever I try putting a background on this tank, either plain shiny or plain matte or decorative shiny, this betta literally does not stop trying to fight himself. Have even tried putting the only spare lamp I had next to the darkest corner, which helps a bit, but if anything goes on that back he can't stop. I don't want him him to stress himself to death. Any tips to stop this reflection, aside from moving the tank? I really want to use a background lol.