right, but thats b/c the side or front doesn't have something that allows the glass to mirror his image. once you block the light from pasing through the glass, there will be SOME level of reflection...... know what i mean? if you reduce the gloss of the background, you will reduce the reflective properties. but even still, the glass will have some reflective properties since light is not passing directly through it as it can on the sides or the front of the tank. try taking the background totally off and replace it with some non-glossy paper and see if the behavior stops. take it from there. you could always paint the background with flat spray paint to reduce gloss.