Figure 1.

Experimental setup used for color discrimination tests. Prior to each trial, the individual was placed in the starting cylinder before it was allowed to approach and dislodge the colored plastic chips. SC, starting cylinder featuring an opaque, light grey and a transparent side; HB, hole-board with 24 equi-spaced holes placed horizontally along the front side. In each trial, 2 holes concealing food were covered with colored plastic chips (red or yellow in guppies, green and yellow in mollies).