In this article the mirror image isn’t really a perfect match, is it? It doesn’t itself secrete anything. Also, could the mirror be made to slowly withdraw, thus pulling the fish image away from the real fish in a simulated retreat? Let’s see then if there are any victory-induced hormones released.

W. Gregory Stewart
Los Angeles, Calif

I may be suggesting the obvious, but it would seem useful for the researchers to try spherical mirrors with their fish to produce the illusion of either larger or smaller opponents when they see their own images.

Dan Lipp
Fort Collins, Colo