My Betta fish is constantly able to see his reflection. I do not keep the lights on in his tank very often as I think that tends to stress him out more. I have tried putting books behind the tank and on the sides but he is still able to see his reflection. I have a round 3.5 gallon tank that sits on my desk in my apartment. If anyone can give me some tips as to how I can eliminate this mirror effect and if you see something wrong with my tank setup I would really appreciate it. Thanks!