Abstract
Currently, there are 11 species of introduced fish established in the inland waters of Western Australia. Most of the introduced fishes found here are the classic ferals, such as members of the Salmonidae, i.e. rainbow trout (Oncorhynchus mykiss) and brown trout (Salmo trutta), Cyprinidae, i.e. goldfish (Carassius auratus) and carp (Cyprinus carpio), Poeciliidae, i.e. mosquitofish (Gambusia holbrooki), one-spot livebearers (Phalloceros caudimaculatus), guppies (Poecilia reticulata) and swordtails (Xiphophorus helleri), Percidae, i.e. redfin perch (Perca fluviatilis), and Cichlidae, tilapia (Oreochromis mossambicus). More recently, the eastern Australian silver perch (Bidyanus bidyanus) (Percichthyidae), which was introduced for aquaculture, has been captured in the Swan River near Perth. The majority of introduced species are confined to the south-west, while three and one species have been recorded from the Pilbara and Kimberley, respectively. Some species are extremely common and widespread, e.g. G. holbrooki and P. fluviatilis, whereas others are far more restricted and may be confined to between one and three catchments, e.g. C. auratus, C. carpio, P. caudimaculatus, P. reticulata, X. helleri, O. mossambicus and B. bidyanus. The impact of these introduced fishes on native species varies but ranges from predation, e.g. O. mykiss, S. trutta, G. holbrooki and P. fluviatilis, to aggressiveness, e.g. G. holbrooki, X. helleri and O. mossambicus, and competition for food and habitat.