Effects of populations of Cyprinodon macularius Baird and Girard (desert pupfish) and Gambusia affinis affinis (Baird and Girard) on aquatic insects and zooplankton were investigated in shallow ponds clear of emergent vegetation and those planted with rice. Presence of both fish caused equivalently lower densities of beneficial insect predators, mosquitoes, and zooplankton.

Except for some behavioral feeding differences, food consumption appeared to be related to the density of food organisms available. Cyprinodon macularius foraged primarily in the benthos, where it consumed chironomid midge larvae, aquatic vegetation, snails, detritus, and some zooplankton and insect predator groups; whereas, G. affinis, foraging more at the surface, consumed a diverse selection of terrestrial insects as well as chironomid midge larvae, more planktonic zooplankters, snails, and some insect predators.

Cyprinodon macularius appears to be an acceptable substitute for G. affinis in mosquito control, and may be preferred in habitats harboring other native fishes due to minimal piscivorous behavior.