Six species of the genus Myxobolus were recorded from estuarine and marine fishes at the New South Wales coast. A species infecting the submucosa in the intestine, intrahepatic bile ducts and gall bladder of Mugil cephalus was tentatively identified as M. cf. spinacurvatura Maeno, Sorimachi, Ogawa and Egusa, 1990. M. rohdei n. sp. was discovered in kidney interstitium of Mugil cephalus. M. purkynjei n. sp. was found in the gill filaments of Girella tricuspidata, while in the kidney and in pyloric caeca of the same host M. girellae n. sp. was detected. M. acanthopagri n. sp. was found to infect the intestine of Acanthopagrus australis. M. conei n. sp. is described from the lumen of bile ducts in the liver of Psetrdocaranx dentex. Masses of plasmodia obstructing the lumen of biliary ducts elicit histopathological changes in the walls of the ducts and in the neighbouring liver tissue. Coelozoic plasmodia are rather unique in the genus Myxobolus, the species of which are tissue dwellers. This paper raises the number of species of the genus Myxobolus found in marine fishes to twenty-nine.
