A Comparison of Natural Sea Water and Artificial Seawater for Keeping Live Fish Intended for Consumption

Abstract:

Goal

This study assesses the quality of artificial seawater and natural seawater and determines which type of sea water is most suitable to keep live seafood intended for human consumption in Hong Kong.

Background

While live fish may be perceived as more fresh by consumers, in 2006 some stalls in wet markets were found to be using flushing seawater (plumbed to homes in Hong Kong for flushing toilets) for keeping live seafood intended for human consumption (Chow, 2006). Partly in response to findings like this and due to previous outbreaks of Escherichia coli and Vibrio sp. from aquatic products, all licensed vendors are now required to follow strict regulations to ensure water quality (FEHD, 2018).

Although there have not been any recent outbreaks, climate change, increased marine pollution, as well as different safety practices associated with increasing cross-border trade, may have increased the risk of contamination.

Methodology

Samples of water will be collected from several different stalls and locations (including representative numbers using synthetic seawater and natural seawater). 3M Petrifilm plates will be used to assay for the presence of E.coli, a 6-in-1 Quicktest 50 (Colombo BV) for the water quality and growth on LB agar to compare total culturable microbial concentrations. CHROMagar Vibrio will be used to identify species such as V. vulnificus, V. parahaemolyticus and V. cholera.

References

Centre for Health Protection .(2010). Food Poisoning Associated with Vibrio Parahaemolyticus in Hong Kong – Current Situation and Recommendations. Hong Kong Special Administrative Region. Available at: https://www.chp.gov.hk/files/pdf/food_poisoning_associated_with_vibrio_parahaemolyticus_in_hong_kong_current_situation_and_recommendations_r.pdf

Kam, K.-M., Leung, T.-H., Ho, Y.-Y.P., Ho, N.K.-Y., Saw, T.A.P. (1995) Outbreak of Vibrio cholerae 01 in Hong Kong related to contaminated fish tank water, Public Health, 109(5), 389-395. doi: 10.1016/S0033-3506(95)80012-3

Chow, Y. (2006). Control Quality of Fish Tank Water. (Press Release LCQ11). Available at: www.info.gov.hk/gia/general/200611/01/P200611010165.htm.

Food and Environmental Hygiene Department (FEHD). (2018). Food Hygiene Code. The Government of the Hong Kong Administrative Region. Available at: https://www.fehd.gov.hk/english/publications/code/allc_6.html