Abstract

Lateral line depigmentation (LLD) is a common condition in tropical fish.^1–2 The opioid receptor antagonist naltrexone promotes wound healing in mice via cytokine production and stimulating angiogenesis and epithelial cell replication.^3–6 One palette surgeonfish (Paracanthurus hepatus) demonstrated clinical improvement after a single topical treatment of 4mg naltrexone and 10g iLEX mixed paste applied in an approximately 2mm thick layer. Seven additional fish subsequently underwent the treatment. Two fish served as controls, and two fish received only topical iLEX. All controls were treated at the end of the study. Severity of disease at start of treatment was scored on a 0–3 scale, and inflammatory response gauged on a 0–3 scale for five days after treatment. Animals that lacked an inflammatory response after topical treatment were administered intradermal naltrexone 4mg diluted into 10mL saline around the lesion. At day 33, animals were caught to evaluate wound size. Smaller lesion sizes in fish with severe LLD after treatment were noted when compared to fish that initially presented with less severe lesions and the “control group”. Animals with mean inflammation scores ≥1 demonstrated smaller lesion sizes compared to animals that did not. Naltrexone cream appears to be effective for treatment of clinical appearance of LLD in palette surgeonfish while facilities investigate and correct the underlying cause of LLD.

Acknowledgements

The authors wish to thank the staff of the Blue Wonders and Animal Health departments at the National Aquarium for their dedication to the care and maintenance of these animals. Thank you to Dr. Natalie Mylniczenko of Walt Disney World, Dr. Shane Boylan of Sea World Abu Dhabi Aquarium for problem solving creative treatment options for LLD and connecting our team, and the husbandry staff at SeaLife Concord for helping to initiate this idea.

Literature Cited

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