Well, there isn't much living space in HK so there isn't a lot of people who have tanks bigger than 40 gallons. In HK, we usually like small size community fish like platies, swordytails and smaller tetras. Some people like carps or cichlids too. Old people tend to keep goldfish and Ranchu goldfish. However, if you keep discus or arrowannas that means you are a rich person because these fish are very expensive.
David, you can search " Goldfish street HK" and see how big the hobby is in Hong Kong. You may be saying you shouldn't be selling fish like this, but I can tell you everything I buy there is in good quality and 3 times cheaper in other aquarium shops.