Diel Activity in the Yellow Bullhead

Abstract

Twelve adult yellow bullheads (Ictalurus natalis) were tested individually in an electronic shuttlebox device (Ichthyotron) to determine their diel activity pattern. Activity, monitored by photocells, was quantified as the bullheads shuttled between the chambers of the device. Data for 3-day tests on all 12 fish were pooled and expressed as hourly percentages of total activity during 24-h periods (12 h light, 12 h dark). Eighty percent of all activity occurred during the dark period, indicating a nocturnal activity pattern similar to that of brown bullheads (I. nebulosus) and black bullheads (I. melas).