Before the 1970s, Yuen Long, Mai Po and most of the northern New Territories were filled with rice paddies. Unlike the hilly landscape in Kowloon or the eastern New Territories, this was a flat and fertile region, where grains glittered at the sunset like a sea of stars. Rice requires a lot of water to grow, so the paddies are flooded -so a group of shrewd farmers made use of those paddies to raise fish. The rice became a natural fish feeder; whenever a breeze stroked across the fields, some of the grains fell into the pond, and the fish would get to taste the first harvest before everyone else.
Nearly half the ponds were filled with grey mullet (wu1 tau2 烏頭). For years, this fish was in high demand for its silky texture and mouth-watering fish oil. According to research by Sidney Cheung, an anthropologist specialising in food, identity and cultural heritage at the Chinese University of Hong Kong, grey mullet was first encountered in Tai Shui Hang, Ma On Shan, when a few fishermen happened to catch a group of baby grey mullet and bring them back to their ponds in San Tin, Yuen Long. The richness of the mullet’s oil and flesh earned the fish a good deal of fame across Hong Kong. Its popularity made it so profitable that between the 1950s and 80s, more and more rice farmers turned their paddies into fish farms.
At its peak in the 1970s, grey mullet was sold for HK$30 per catty (about 600 grams), which would be equivalent to HK$300 today. Fishermen could earn several thousand dollars a month just from mullet and other freshwater fish. But those fortunes were short lived. There are no fishing tycoons in today’s Hong Kong; grey mullet costs just HK$15-18 per catty. The price plummeted after the government opened up the market to mainland imports, and the relatively high cost of raising fish in Hong Kong made local fish uncompetitive.
That was especially true for grey mullet, which are fed with peanut bran and bread crumbs instead of unknown chemicals, so as to enhance the growth of the layers of oil on their back. The grown-ups swim so swiftly that they can escape almost all kinds of nets. But there was another reason for the decline of the grey mullet’s popularity: farming techniques left many fish with an unpleasant muddy taste, which many people cannot stand, and the reputation of grey mullet was ruined for generations.
It takes between 10 to 14 months for a grey mullet to mature. The time it takes to grow is one thing, but the time fish farmers spend catching the baby mullet in the first place is quite another. Every year, they have only one shot to catch the baby mullets which are also known as fry. Every winter, mother mullets escape the colder waters around Panghu in Taiwan and swim south to Sai Kung in Hong Kong. They lay eggs in the middle of the sea around the time of Chinese New Year. Once the babies hatch, they happily swim around Hong Kong’s eastern waters. The Yuen Long fishermen have then to travel all the way to Sai Kung, check whether the baby mullet have arrived, bring them back to the fish ponds and make sure they are safe and sound. With climate change and fluctuating weather of recent years, it is not uncommon to find 25 percent of the fry dead before they have even been sorted into the ponds.
Grey mullet is one of the rare species that can adapt to both saltwater and freshwater. Making the ponds inhabitable for them requires something similar to an aquarium swapping tank. The trick is to provide a series of buffer zones, mimicking the transition from saltwater to freshwater in the wild.
However the decline in popularity of local grey mullet truly began when the old method of pond management had dramatically altered the taste of the fish. When the soil surrounding the pond went stale and polluted the water, the mullet absorbed the earthiness into its blood and flesh. This undesirable taste was so strong that it covered every taste bud. It was like eating dirt. So many people found it so off-putting, they avoided mullet in their trips to the fish market, leaving the fish to only a small group of diehard fans.
Over the years, after trying many methods and failing on many occasions, fish farmers finally identified the problem and devised a system similar to crop rotation. To make sure the earthiness does not penetrate the fish, they keep the pond water fresh, clean and filled with nutrients. That may sound easy, but a natural pond is not a fish tank: every three months, the farmers empty the water from one of the ponds to another, and use an excavator and bulldozer to reshape and deepen it to the same level as it was three months earlier. This is best done in autumn and winter when the air is dry. It works best on sunny days, in order to dry the pond soil until it is firm. The rays of the sun kill lingering bacteria, so the pond is sterilised without having to use any chemicals.
Apart from these new pond maintenance techniques, another way to preserve the tenderness for which grey mullet has become famous is to catch them at the right time of the day and be extremely careful in handling them. “You must fish at night instead of daytime, and you have to wait until both the sun and the water temperature go down,” says Yuen Long fish farmer Kwok Mok-tai. “When you fetch them out of the net and scramble a school of them, they feel suffocated, the heat soars, their muscles contract even more, and they might have died long before being stored in ice water. Then you will lose both the tenderness and the good taste.”
Although the grey mullet hasn’t gained back its moment of glory, its tenderness still makes it a favourite for many. The most popular way to cook grey mullet is to steam it with dried mandarin peels (chan4 pei4 陈皮) and shredded ginger. If you are not a fan of those spices, you may try the simplest method, which is to wash and rub the mullet with a handful of salt, wrap it with foil without rinsing and slowly bake it for about 30 minutes at 200 degrees Celsius. Either way, you cook the fish without wasting a drop of its precious yellow fish oil, and you’ll avoid destroying the silky smoothness of its flesh.