Abstract: This study was undertaken to experimentally test for evidence of optimal foraging in guppies, Poecilia reticulata. Foraging preferences of guppies feeding on brine shrimp were studied to make predictions about optimal diet breadth. First, the profitabilities (Engery intake/ handling times) were determined by testing the handling time of four size classes of guppies foraging on brine shrimp of sizes 2, 4, 6, and 8 mm. The following week, we tested whether guppies of various sizes prefer prey that …showed first 75 words of 660 total…

…showed last 75 words of 660 total…were gathered. A small aquarium was set up with 15 prey items arbitrarily placed in 15 quadrants. Included in the prey items were 5 small, 5 medium, and 5 large prey items (medium size being the optimal size calculated from week one). A single guppy was placed into the aquarium and was allowed to forage. The order of which size prey eaten was recorded. This process was repeated three times with different guppies for each of the four size classes.