Originally Posted by Sweeda88
Not true. I've seen PLENTY of Betta at Walmart flaring at the other fish.
Its 100% true... its called Snell's Law or http://en.wikipedia.org/wiki/Angle_of_refraction
... or simply get a glass of water and look thru it, only the image near the axis of the glass is clear, everything away from the axis becomes more and more distorted.
Now that is not to say that if both fishes are near the wall of the cup/jar, that they then aren't able see each other, but when fishes are past the half way point of the jar, it is unlikely that they will see each other