37
CHAPTER 3
SURVEY OF PARASITES IN THE AUSTRALIAN ORNAMENTAL FISH
TRADE
Abstract
The ornamental fish trade provides a pathway for the global translocation of aquatic parasites.
I examined a total of 1,020 fish imported from southeast Asia, including freshwater and
marine fish species, for myxozoan and monogenean parasites.
Fish were received following
veterinary certification that they showed no clinical signs of pests and diseases from the
exporting country and visual inspection at Australian border control. Myxozoan parasites
infected 8 of 13 freshwater populations and 8 of 12 marine populations. 18 putative types of
myxozoan parasites and 14 putative types of monogenean were identified using a combined
morphological and molecular approach. A total of 12 morphologically distinct Myxobolus
spores were detected amongst all Carassius auratus Linnaeus, 1758 populations. Myxidium
spores were detected in Helostoma temminckii Cuvier, 1829, and four putative Ceratomyxa
sp. spores were detected in Cheilodipterus quinquelineatus Cuvier, 1828, Pterapogon
kauderni Koumans, 1933, and Zoramia leptocantha (Bleeker, 1856). Monogenean diversity
included seven Dactylogyrus spp. (including Dactylogyrus vastator Nybelin, 1924), and three
Gyrodactylus spp. infecting goldfish, C. auratus. Dactylogyrus ostraviensis Řehulka, 1988,
infected rosy barb, Pethia conchonius Hamilton, 1822, while two Trianchoratus spp. infected
three spot gourami, Trichopodus trichopterus Pallas, 1970 and pearl gourami Trichopodus
leerii Bleeker, 1852. Urocleidoides reticulatus Mizelle et Price, 1964, infected guppy,
Poecilia reticulata Peters, 1859. Australian import conditions require mandatory treatment
for goldfish with parasiticide (e.g. trichlorfon, formaldehyde, sodium chloride) for the
presence of gill flukes (D. vastator and Dactylogyrus extensus Mueller et Van Cleave, 1932)
prior to export. The discovery of myxozoan and monogenean infections, including D.
vastator in goldfish, show that pre-export health requirements and visual inspection did not
reliably prevent parasite infections. Inspection prior to exportation and at border control must
account for the highly cryptic nature of parasites and consider alternatives to current pre-
export conditions and visual inspection at border con