The food of the New Zealand common river galaxias, Galaxias vulgaris Stokell (Pisces: Salmoniformes)

Abstract

The food of the common river galaxias, Galaxias vulgaris Stokell, inhabiting the Glentui River, Canterbury, New Zealand, was studied between June 1970 and November 1971. Basic food consisted of Ephemeroptera: particularly the larvae of Deleatidium spp., Coloburiscus humeralis and Nesameletus ornatus. Secondary food consisted of Elmidae (Coleoptera), terrestrial arthropods, and the larvae of Rhyacophilidae, Hydropsyche colonica, Olinga feredayi, Pycnocentrodes aureola (Trichoptera), Archichauliodes diversus (Megaloptera), Chironomidae and Simuliidae (Diptera). Other food items were considered to be incidental. Diet varied seasonally and with size of fish. Large fish tended to eat larger food items than small fish, and there was also an increase in variety of food items with increase in fish size. Recently hatched fish fed predominantly on dipteran larvae, changing to a mainly ephemeropteran diet on moving to the adult habitat. Diet did not change significantly with age in fish sampled in the same type of habitat. Male and female diets were very similar.