I visited the Clear Water Country Park, an area the juts out from the Kowloon Peninsula into the South China Sea on the east side of Kowloon. We walked above the fishing village of Po Toi O where many aquaculture plots were seen. Small fish are put into the enclosures and very little feed is actually required and when they are a good size they are sold, providing quite a good living for local villagers. Fishing regulations are very lax in Hong Kong–even more so than China. In New Zealand it is a very rigorous process for getting a license to establish aquaculture plots–research on flow of water, etc. need to be done. In Hong Kong the locals are able to continue to put the plots in the same place with high levels of fish droppings below.
In spite of this, on this east side of Hong Kong, the fish are good. A strong current comes down past Taiwan and washes out the toxins on this side of the Hong Kong. A great deal of pollution is released into the waters on the west side because of all the industrial development in the Pearl River Delta. The only way to know for sure where your fish come from is to go to a restaurant right by the waterfront 🙂