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Email the author (Login required) Effect of salinity and chemical treatments against egg and oncomiracidia larvae development of Rhabdosynochus viridisi in Centropomus viridis (Teleostei: Centropomidae)
Submited: 2025-11-04 22:56:05 | Published: 2026-06-30 22:44:54
DOI: https://doi.org/10.3856/vol54-issue3-fulltext-3565
Abstract
This study evaluated the effects of salinity and chemotherapeutic treatments on the embryonic development and hatching of Rhabdosynochus viridisi, a diplectanid monogenean ectoparasite of the Pacific white snook (Centropomus viridis). Egg morphology, oncomiracidial features, and larval development were also described. Naturally infected fish were collected during a parasitic outbreak and maintained in 500 L seawater tanks. Eggs were obtained using cotton threads and incubated to obtain oncomiracidia. Incubation time was 96 h at 35 ppt and 23°C, and larval longevity ranged from 96 to 120 h at 23°C. Three chemotherapeutic agents-Dermo-gard® AQUA (0.2 g L-1), formalin (170 mg L-1), and albendazole (20 mg L-1)-and six salinity levels (0, 7, 14, 21, 28, and 35 ppt) were tested. Treatments were applied to eggs and oncomiracidia in triplicate at 23°C. Formalin (170 mg L-1) significantly inhibited embryonic development (P < 0.001) and eliminated oncomiracidia within 1 h (P < 0.0002). However, no development or survival occurred at 0 of salinity (P < 0.000001), indicating that freshwater exposure is more effective than chemical treatments in larvae after 15 min. These results provide baseline biological information for R. viridisi and support the use of low salinity as an effective strategy for controlling monogenean infections in aquaculture.
