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Diseases of Aquatic Organisms

    DAO prepress abstract   -  DOI: https://doi.org/10.3354/dao03435

    Effects of skin abrasion in immersion challenge with Vibrio harveyi in Asian seabass Lates calcarifer fingerlings

    Y. K. Chin, M. Y. Ina-Salwany, M. Zamri-Saad, M. N. A. Amal, A. Mohamad, L. Jing-Yie, S. Annas, Nurhidayu Al-saari*

    *Corresponding author:

    ABSTRACT: Skin abrasions often occur in farmed fish following handling by labourers, injury by farm facilities, cannibalism and ectoparasites. Vibrio spp. are an opportunistic pathogen that can invade host fish through damaged tissues and cause outbreaks of vibriosis. This study describes the effect of skin abrasions on the infectivity of Vibrio harveyi using Asian seabass Lates calcarifer (Bloch, 1790) fingerlings as a case example and compares bacterial load and fish survival following immersion challenge with different doses. A total of 315 fish (6.67 ± 1.8 g) was divided into 3 treatments: skin abrasion followed by immersion infection, immersion infection alone and an uninfected control. Fish in the infection treatments batch were divided into three subgroups and exposed by triplicate to a 7 d immersion challenge with 1 × 106 CFU ml–1, 1 × 107 CFU ml–1, and 1 × 108 CFU ml–1 of live V. harveyi. No mortalities were observed in the control and immersion infection groups. However, fish in the skin abrasion treatment group that were infected with 108 CFU ml–1 live V. harveyi showed signs of progressing disease throughout the experiment, which resulted in mortalities. Significantly higher bacterial loads (p < 0.05) were recorded in the intestine, liver and gills of the fish in this group. Fish in the skin abrasion treatment that were exposed to 107 and 108 CFU ml–1 of V. harveyi showed 100% mortality by Day 5 and 4, respectively. These findings confirm that skin injuries increase seabass fingerlings’ susceptibility to V. harveyi infection.