Characterisation of nematode larvae found in a vulnerable native Australian fish, the southern pygmy perch, Nannoperca australis Günther

Abstract

Context The southern pygmy perch (Nannoperca australis) is an endemic freshwater fish in Australia that is facing population decline and is listed as endangered or vulnerable in several states. Aims The aim of this study was to investigate the presence of parasites in the southern pygmy perch population and provide insights into their effect on the health and conservation of the species. Methods In total, 81 southern pygmy perch specimens were examined for parasite infections, followed by characterisation of the parasites. Key results The postmortem examination of the fish specimens did not show any visible parasites. However, through the incubation method, nematode larvae were discovered in 14 fish (mean intensity 1.6, mean abundance 0.28). Conclusions This study represents the first report of nematode larvae belonging to the genus Spiroxys in Australia, specifically in the southern pygmy perch. These findings highlighted the presence of parasite infections in the endangered southern pygmy perch and underscored the importance of conducting further research on parasites and their potential effect on the health and conservation of this species. Implications The discovery of nematode larvae in the southern pygmy perch raises concerns about the potential effects of parasites on the population.