Emamectin Benzoate Treatment of Hybrid Grouper Infected With Sea Lice in Hong Kong

Abstract

Sea lice (Copepoda: Caligidae) are ectoparasites which negatively impact marine aquaculture species around the world. There are a limited number of treatments licensed for use against sea lice in tropical and semi-tropical farmed fish species. Emamectin benzoate (EB) was an effective pharmaceutical drug against sea lice infestations in several salmon industries before resistance to the product developed. This drug has not been extensively tested in marine fish within Asia. The objective of this study was to determine whether this drug could be used to treat oral infections with sea lice in hybrid grouper (Mycteroperca tigris × Epinephelus lanceolatus) cultured in saltwater net-pen sites in Hong Kong. We observed an overall reduction in sea lice infections over time, starting on the last day of the treatment up to the end of our study (i.e., 14 days after the last EB treatment). We also observed a large variation in concentrations of EB in fish on the last day of the treatment, which provides an explanation for the variation in response to the treatment. It also suggests that distribution of the medication to fish in saltwater net-pens is difficult, especially when medication is hand-mixed in the feed and possibly unevenly distributed in the daily rations. Overall, this study provides preliminary evidence that EB could be used to treat sea lice found in Hong Kong and potentially in other regions of SE Asia.

Neurodevelopmental Toxicity of Emamectin Benzoate to the Early Life Stage of Zebrafish Larvae (Danio rerio)

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Infectious diseases reported in warm‐water marine fish cage culture in East and Southeast Asia—A systematic review

“…In addition, infections with Caligus spp. in grouper in Asia often report oral lesions (St‐Hilaire et al, 2021). Lesions on the body and head regions of fish can also lead to reduced growth.…”

Antiparasitic approaches and strategies in European aquaculture, with emphasis on Mediterranean marine finfish farming: Present scenarios and future visions

“…Similar results have been reported for the coelomic nematode Philometra rubra in wild‐hatched striped bass ( Morone saxatilis ) 174 and for controlling natural infestations of copepods in economically important farmed fish species of India 175 . The high antiparasitic value of EMB has also been demonstrated in marine finfish reared in either a cold environment with C. curtus infestations in Atlantic cod ( Gadus morhua ) 176 or in warmer water against Caligus spp.‐infected hybrid grouper ( Mycteroperca tigris × Epinephelus lanceolatus ) 177 …”

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