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Email the author (Login required) Co-infection outbreak of tilapia fish farm associated with severe mortality during summer in Sinaloa, Eastern Pacific: case study
Submited: 2025-03-12 13:47:06 | Published: 2026-03-18 15:53:19
DOI: https://doi.org/10.3856/vol54-issue2-fulltext-3409
Abstract
This study aimed to describe the mass mortality of farmed Nile tilapia (Oreochromis niloticus) associated with co-infections during summer in Sinaloa, on the northwest coast of the Mexican Pacific. In July 2023, a parasitic infection occurred at a Nile tilapia farm, coinciding with an increase in water temperature and a decrease in dissolved oxygen, resulting in fish mortality. The fish farmers applied treatments to eliminate the infection and halt the deaths; however, fish continued to die for several days. Thirty moribund fish were collected for laboratory examination and histopathological analysis. The fish showed signs of emaciation, lethargy, and skin abrasions. Parasitological analysis identified ectoparasites, the most abundant of which were peritrichous ciliates on the gills and the host fish's epithelium. Five species were identified: Trichodina hypsilepis, T. magna, T. nigra, Trichodina sp., Ambiphrya sp., and one unidentified protozoan. The monogeneans Gyrodactylus cichlidarum and Ciclydogyrus sp. were identified, as well as Pseudomonas sp. (probably as a secondary agent). Histopathological examination of the fish gills showed that the protozoan attached to the gill filaments caused severe hyperplasia and gill epitheliocystis. The mortality event lasted 10 days, reaching 50,000 deaths (5,000 dead fish per day). Parasitic infections have significant consequences for farmed fish species and should be considered a fundamental factor in any aquaculture system.
