Causative agent: Myxobolus cerebralis — myxozoan parasite
Whirling Disease is an exotic disease that Australia has thus far successfully excluded through strict biosecurity measures — and for very good reason. Caused by the myxozoan parasite Myxobolus cerebralis, the disease has caused catastrophic declines in wild trout populations across North America and parts of Europe wherever it has been introduced. The parasite infects the cartilage of juvenile salmonids, causing neurological and skeletal damage that results in the distinctive spinning and whirling swimming behaviour for which the disease is named. Infected fish develop bent spines, deformed jaws, and darkened tails, and mortality in young trout and salmon can be very high. Critically, the Tubifex worm — commonly sold as a live food in Australian aquarium shops — serves as an intermediate host for the parasite. Australian biosecurity authorities actively work to prevent the import of infected fish, fish eggs, and potentially contaminated substrate or live foods. Any Australian fish keeper who suspects whirling disease in their salmonid fish must report immediately to the Department of Agriculture, Fisheries and Forestry.
Symptoms
- •Whirling or spinning swimming behaviour
- •darkening of the tail (black tail disease)
- •skeletal deformities
- •bent spine
- •abnormal jaw development
- •stunted growth in juveniles
- •mass mortality in young fish
Treatment
- •No effective treatment — EXOTIC disease not established in Australia. Strict biosecurity measures prevent entry. Report any suspected case immediately to DAFF.
Australian Medications
- •No treatment available — EXOTIC DISEASE
- •report immediately to DAFF if suspected
Commonly Affected Fish
- •Salmonids (rainbow trout, brown trout, Atlantic salmon, grayling)
- •juvenile fish most severely affected
Important Notes
EXOTIC — NOT ESTABLISHED IN AUSTRALIA. Tubifex worms are an intermediate host — source live foods carefully. Report any suspected case to DAFF immediately.