its hard to say size but the background panels are 24" my tank is 362 tall and when he swims up the side wall he is near the full height but 36 tall means you get about 32 of water
Correct me please if I am wrong, but I always thought (and I thought I read) the opposite.
A fish appears the biggest in a spherical fishbowl, which acts like a convex lens and gives a magnified virtual image of the fish because of the refraction.
In a perfectly rectangular tank, the fish only appears at a smaller depth than they really are, that is closer to you and so does the back wall as well. But the glass panel bends and this places it between a bowl and a perfectly flat rectangle viewing panel. Hence, the more it bends, the larger the exaggeration.