Isolation and characterization of Vibrio spp. from fish and packing water associated with ornamental fish exports.

Abstract

Ornamental fish export trade being a thriving industry, its substantial contribution to the Sri Lankan economy underscores the necessity to address the associated issues. Presence of pathogenic Vibrio spp. in export fish and packing water is a critical concern as they can pose public health hazards while failing to comply with quarantine regulations during export, leading to economic losses. The objective of this study was to isolate and characterize Vibrio spp. associated with fish and packing water in the ornamental fish export trade, to assess its microbial safety. Fish (n = 20) and packing water (n = 41) samples received by the Veterinary Investigation Center, Welisara for routine quarantine certification during the period from August to October 2023, were used in this study. Fish were dissected and bacterial cultures were attempted from internal tissues while water samples were pre-enriched in alkaline peptone water, before culturing. All cultures were attempted on Thiosulphate Citrate Bile-salts Sucrose agar at 37℃ for a period of 24 hours. Bacterial colonies isolated were characterized by employing a series of biochemical tests. The occurrence of Vibrio spp. in samples obtained from different districts in Sri Lanka and different sources, were analyzed and compared by using Chi-square test. Vibrio spp. was isolated from both fish (10%; 2/20) and packing water (24.4%; 10/41). All Vibrio isolates from fish samples were identified as V. cholerae. The occurrence of V. cholerae in packing water samples tested was 60% (6/10) while it was 40% (4/10) for V. parahaemolyticus. There was no difference in the occurrence of Vibrio between samples received from different districts and between freshwater and marine fish tested (p > 0.05). In conclusion, Vibrio cholerae and Vibrio parahaemolyticus were isolated from ornamental fish and packing water samples. Remedial measures were suggested to the relevant ornamental fish farms to rectify the situation.