First report of mass mortality in hatchery-reared Sabah Pelian (Tor sp.) attributed to Aeromonas veronii in Sabah, Malaysia

Chin, Grace Joy Wei Lie and Kenneth Francis Rodrigues and Ching, Fui Fui and Helena Biun and Azhar Kassim and Rafidah Othman (2024) First report of mass mortality in hatchery-reared Sabah Pelian (Tor sp.) attributed to Aeromonas veronii in Sabah, Malaysia. Malaysian Journal of Microbiology, 20. pp. 712-719. ISSN 1823-8262

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Abstract

A breeding program for Sabah Pelian (Tor sp.) was initiated at the Universiti Malaysia Sabah (UMS) Hatchery Facility in July 2023. Fifteen Tor sp. were obtained from the Pagalan River, Tambunan, Sabah, and transported to the UMS Hatchery. After 12 days of acclimatization to the hatchery's conditions, followed by two days of heavy thundershowers, mass mortality was recorded on day 14. The goal of this study was to identify the cause of Pelian's mass mortality in the UMS Hatchery facility. The study involved the dissection of dead fish samples to assess internal organ conditions and the isolation of bacteria on microbial media. Despite normal water quality assessments, post-mortem examinations observed external skin lesions, haemorrhages and excessive mucus covering the body of the dead fish. Histopathological examination indicated a necrotizing inflammatory response in the ovarian tissue. Aeromonas veronii was isolated and identified as the causative agent through biochemical and molecular methods. Additionally, the antibiotic sensitivity test indicated varying degrees of susceptibility of A. veronii to the tested antibiotics. The bacterium showed resistance to ampicillin and erythromycin, while the remaining antibiotics exhibited sensitivity or an intermediate range of effectiveness. The two-day adverse weather prior to the mortality event was identified as the primary stress factor that likely induced the A. veronii infection, resulting in mass mortality of the Pelian. The study highlights the significance of understanding the interaction among fish, their internal microbiota and external environmental factors that may induce pathogenicity.

Item Type:	Article
Keyword:	Aeromonas veronii, Antibiotic resistance, Bacterial infection, Sabah Pelian, Tor sp.
Subjects:	S Agriculture > SH Aquaculture. Fisheries. Angling > SH1-691 Aquaculture. Fisheries. Angling > SH20.3-191 Aquaculture > SH151-179 Fish culture
Department:	INSTITUTE > Borneo Marine Research Institute
Depositing User:	DG MASNIAH AHMAD -
Date Deposited:	31 Oct 2025 16:50
Last Modified:	31 Oct 2025 16:50
URI:	https://eprints.ums.edu.my/id/eprint/45563

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