Ectoparasite infections are major production limiting issues in aquaculture. The only products permitted for use in Australia against ectoparasites of finfish are formalin, sodium percarbonate and hydrogen peroxide. These products can have negative effects on fish gills and skin and result in direct mortality when elevated chemical dose or duration of exposure are sub-optimal or improperly calculated. Against some flatworm parasites formalin, sodium percarbonate and hydrogen peroxide have low efficacy. Praziquantel (PZQ) immersion treatments have been found to be both safe and efficacious for current fish flatworms applications, at a low dosage and duration of exposure, with a lesser or equivalent environmental impact. The aquaculture industry and the Subcommittee for Aquatic Animal Health identified access to PZQ for finfinfish as a priority. Treatment forms a vital part of parasite management in aquaculture along with husbandry practices designed to interrupt parasite lifecycles. Appropriate use of PZQ can help alleviate reduced growth and food conversion and improves welfare associated with flatworm parasite infestation. A permit obtained as part of this project will facilitate better parasite management, improve production and fish welfare. APVMA provided pre-application advice on PZQ. Available data for PZQ can satisfy the APVMA module requirements for efficacy, chemistry and manufacture, toxicology, trade and occupational health and safety. These are available in published literature, a range of industry studies of animals treated off-label and laboratory studies. There is a lack of data to satisfy the requirements mainly in the environment modules and the target animal safety module.

PZQ is registered as an active ingredient, and for use in cats, dogs, horses, cattle, pigs and sheep in Australia. An unregistered product is manufactured by VetLab Autopak into two permitted products for use in kingfish as an in-feed (PER#87336) or immersion (PER#87833) treatments. The APVMA PAA assessed PZQ as suitable for assessment for use in finfish.