Helminth parasitism of Galaxias maculatus (Jenyns 1842) in southwestern Australia

One cestode, Ligula sp. [possibly Ligula intestinalis (L.)], one trematode, Diplostomum sp., and two nematode parasitic worms, Eustrongylides sp. [possibly Eustrongylides gadopsis (Royal Society of South Australia, 64, 340)] and Contracaecum sp. are reported from Galaxias maculatus inhabiting a permanent freshwater lake and two intermittently flowing, saline rivers in southwestern Australia. Worms infecting fish are all larval; the definitive hosts are piscivorous waterfowl. Ligula sp. infected 12% of fish in the lake. Effects of infection include reduced lifespan, significant weight reduction of gonads of males and females and body weight of females. Infection reduces the proportion of males that attain spawning gonad stage more severely than it does in females. The prevalence and intensity of Ligula sp. infection were much less in the rivers. The infection of Pseudogobius olorum (Sauvage 1880) by this cestode is reported for the first time in Western Australia. Trematodes were much more benign in their effect on G. maculatus.