SPRINGTIME FOODS OF BONYTAIL (CYPRINIDAE: GILA ELEGANS) IN A LOWER COLORADO RIVER BACKWATER

摘要

Bonytail, Gila elegans, in Cibola High Levee Pond, an isolated lower Colorado River backwater, fed more during evening and after dark than during daylight. Fish were omnivorous, and contents of stomachs (n = 72) included amorphous organic matter (materials digested beyond visual identification), aquatic macrophytes, invertebrates (micro-crustaceans, insects, and crayfish), bullfrog, and fish. Proportion of plants decreased while that of invertebrates increased with increased size of fish. Remains offish were found only in the largest specimens. Asian tapeworm, Bothriocephalus acheilognathi, was in 11% of the sample and represents the first report for this parasite from open waters of the lower Colorado River system.