Welfare of saltwater finfish in Hong Kong wet markets 

Year: 2021

Desiree Hung 
City University of Hong Kong

Supervisors: Kwok Zu Lim, Chi Fai Leung, Stephen Chi Ho Chan and Sophie Natasha St. Hilaire 

HSA Student/Trainee Scholarship 2021

The welfare of saltwater fish species in Hong Kong wet markets is often overlooked.  The objective of this study was to investigate the level of fish welfare in these types of markets and determine if any welfare indicators were associated with water quality parameters, and stocking density. Welfare issues observed in long-term holding tanks were ulcerations on the facial and lateral areas, fin erosion, and loss of equilibrium.  Only a few dead fish were observed during our visit to 15 commercial stalls.  Results for water quality parameters in 47 tanks from the 15 stalls were within normal range for most warm water fish species; however, all stall owners used supplemental air or oxygen in their tanks. Stocking density was categorised into one of three groups, and we found a significant association between higher stocking density scores and unionised ammonia levels, facial and lateral ulcerations, and fin erosion. This is consistent with physical damage from overcrowding.  Loss of equilibrium was associated with water quality parameters but the precise mechanism for the issue was not clear.  We hypothesised that the equilibrium issue may be related to a carbon dioxide problem, given the relationship with pH, but we could not measure this dissolved gas during our visits to confirm.  Overall, the welfare of fish in the stalls we visited was acceptable, and the few health issues can likely be addressed directly or indirectly by reducing the density of fish in the tanks.