Thermoregulatory behavior of a tropical reef fish, Zebrasoma flavescens [Acanthuridae, Hawaiian surgeonfish, Laipala, electronic shuttleboxes, Ichthyotron]

Ten Hawaiian "Laipala" surgeonfish (Acanthuridae), Zebrasoma flavescens (Bennett), were tested individually in electronic "Ichthyotron" shuttleboxes for ability to thermoregulate behaviorally. The fish exhibited a diel rhythm of preferred temperature, with a minimum of 19 deg C at midnight and a maximum of 23 deg C at noon. The 24-h mean final thermal preferendum was 21 deg C, similar to the final preferenda of temperate "cool-water" fishes. The similar thermoregulatory behavior of tropical marine and temperate freshwater fishes suggests that thermoregulatory ability is phylogenetically conservative and not strongly influenced by thermal stability of the environment.