Diet in odacid and aplodactylid fishes from Australia and New Zealand

Abstract

Diets of a number of temperate-water reef fishes considered to be herbivores were examined by stomach content analysis. Two species of the genus Odax (family Odacidae), O. pullus and O. acroptilus, were investigated. Stomach contents of samples of O. pullus from two times and two localities on the New Zealand coast were dominated by fucoid and laminarian algae. There was evidence of selection of reproductive structures of fucoid algae as an important food source. O. acroptilus collected from the central NSW coast of Australia proved to be a carnivore on small benthic invertebrates. In addition, the stomach contents of a taxon unique to Southern Hemisphere waters, Aplodactylus arctidens (family Aplodactylidae), and of one member of a widespread taxon, Girella tricuspidata (family Girellidae), were examined as a comparison with Odax. Collections of each species were made in northern New Zealand. A. arctidens and G. tricuspidata were facultative herbivores with diets dominated by under storey and epiphytic red algae. These results emphasize the unusual feeding patterns of herbivorous odacids and their importance in the development of general models of piscine herbivory.