Microbothriid (Monogenean) Infection and Treatment in Captive Blacktip Reef Shark (Carcharhinus melanopterus)

Unlike other microbothriid monogenean infections in elasmobranchs, limited information is available on the biology and treatment of Dermophthirius melanopteri. As parasitic infection with D. melanopteri was found in 21 juvenile blacktip reef sharks (Carcharhinus melanopterus) at the Lotteworld aquarium in Seoul, South Korea, we aimed to investigate the anatomical features and treatment protocols for D. melanopteri in this study. The parasites were sampled and fixed in 10% neutral-buffered formalin, and examined using light and scanning electron microscopy. The treatments included short-term praziquantel baths, freshwater immersion, and long-term trichlorfon baths. Manual removal of parasites was also attempted. Examination and manual removal revealed that, similar to other microbothriids, D. melanopteri attaches to the placoid scale using opisthaptoral secretion in the posterior region. The effectiveness of the treatments varied, with trichlorfon proving the most effective and safe option for complete parasite eradication. Praziquantel facilitated parasite removal by weakening their attachment, suggesting the potential for higher doses and prolonged exposure times for enhanced antiparasitic effects. To our knowledge, this is the first study providing the microscopic details of D. melanopteri infection and its treatment outcomes in captive blacktip reef sharks, thereby providing valuable insights for future research and management.