Haematozoa of wild catfishes in northern Australia.

Very little is known about the diversity, prevalence, or pathogenicity of haematozoa in Australian freshwater fishes. Blood smears from 189 native catfishes, of six different species, from northern Australia were examined for haematozoa. Haematozoan infections were observed only in fishes from Queensland, at an overall prevalence of 0.191 (95% CI = 0.134-0.265). Intraerythrocytic haemogregarines were present in from the Brisbane River at a prevalence of 0.35 (0.181-0.567). Trypanosomes were present in species from four rivers, at prevalences ranging from 0.111 (0.020-0.330) to 1 (0.635-1), and in from one river in Queensland, at a prevalence of 0.063 (0.003-0.305). The haematozoans observed appeared to have little impact on their hosts. spp. were significantly more likely to be infected with trypanosomes, suggesting a high parasite-host specificity. This is the first widespread survey of wild Australian freshwater catfishes for haematozoa, resulting in the first report of haemogregarines from Australian freshwater fish, and the first report of trypanosomes from and