Health status of ornamental freshwater fishes imported to South Africa: a pilot study

摘要

Keeping fish is a popular pastime in South Africa and the majority of ornamental fish are imported. A pilot study was initiated to examine the health status of ornamental freshwater fishes imported to South Africa. Four groups of thirty fish each were examined for the presence of external parasites, and processed for virus isolation and for bacterial and mycobacterial culture. The groups consisted of goldfish (Carassius auratus), koi (Cyprinus carpio), guppies (Poecilia reticulata) and cardinal tetras (Cheirodon axelrodi). Mycobacterium fortuitum was isolated from the goldfish and koi. No other significant bacteria were isolated and virus culture was negative for all groups. Skin scrapings and wet gill preparations were made to detect external parasites. Parasites were identified from fixed material. External parasites included Trichodina mutabilis, Ichthyophthirius multifiliis, ciliophorans of the genus Tetrahymena, and monogeneans belonging to the genera Dactylogyrus and Gyrodactylus. This is the first report of Trichodina mutabilis in South Africa. Diseases imported with ornamental fish pose a risk to both indigenous fish populations and the aquaculture industry.