Milbemycin Oxime (Interceptor®) Treatment of Amphipod Parasites (Hyperiidae) From Several Host Jellyfish Species
On 28 June 2012, 36 wild-caught Crystal jellyfish (Aequorea victoria) from the coast of Victoria, British Columbia arrived at the John G. Shedd Aquarium. It was later discovered that these jellyfish were infested with hyperiid amphipods (Hyperia medusarum). All hyperiid amphipods are believed to be obligate parasites of gelatinous zooplankton during their development.2,3,5 In this case, the amphipods were introduced into a system containing several jellyfish species. Commonly used chemotherapeutics, such as copper and formaldehyde used to eradicate ectoparasites from fishes are generally not tolerated by aquatic invertebrates, such as jellyfish.1 Therefore, the decision was made to use milbemycin oxime (Interceptor® tablets for dogs 50–100 lb, Novartis Animal Health US, Inc., Greensboro, NC, USA), a treatment prescribed for red bug (Tegastes acroporanus) infestation in corals.4
The affected systems received two treatments using one 25 mg aliquot of Interceptor® per 10 gallons of tank water, 6–7 days apart.4 A third treatment was scheduled; however, Interceptor® became no longer available at this time. Despite this, overall treatment to eradicate the parasite from the affected systems was successful. Although the majority of species endured the treatment with no obvious adverse effects, further studies evaluating the tolerance of jellyfish to milbemycin oxime, particularly in small juvenile E. indicans and A. aurita, are warranted. Overall, there were potentially more negative effects associated with the treatment in the hydrozoans than the scyphozoans. Further studies using a different milbemycin oxime product would be beneficial.
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