Meet Mohd Ridzwan Ishak, 45, the oyster man of Bujang Valley, Kedah.

He is culturing about 60,000 oysters in Sungai Merbok, a 45km-long river running with clear, emerald green water because of the 3,000ha of mangrove forest lining much of both banks.

When tourists board his floating farm, many cannot help but sport cheekily expectant grins since the pleasures of this delicacy extend beyond just their palatability: These succulent bivalve molluscs are renowned as aphrodisiacs thanks to a fable that Giacomo Girolamo Casanova, the 18th-century playboy, ate 50 of them for breakfast every day to stay hot and bothered.

In 2005, American and Italian scientists discovered some truth to this old wives’ trick of carnal enhancement. That briny-metallic flesh contains two rarely found amino acid chains that, when fed to male and female lab mice, caused them to have higher levels of the sex hormones testosterone (male) and progesterone (female).

Mohd Ridzwan’s farm is by the riverbank of Kampung Sungai Batu Besi, a tiny village of only about 20 homes in Bujang Valley. This village has ancient origins lost in history. It is near the Sungai Batu archeological site, where there are ruins of an iron smelting town that existed around 480BCE, over 13 centuries before the founding of the Kedah Sultanate in 1136CE.

Though connected to the world by a hard-packed dirt road, the village is so remote that it is hard to give directions and those who wish to visit are supplied the GPS coordinates instead (latitude 5.684233, longitude 100.456920).

Tan (right) and Eryzal observing Mohd Ridzwan as he agitates an oyster cage to clean it.

Assoc Prof Dr Eileen Tan (right) and Eryzal observing Mohd Ridzwan as he agitates an oyster cage to clean it.

Mohd Ridzwan has lived here all his life and is one of only 10 oyster farmers in Peninsular Malaysia.

He started the farm with three friends four years ago. He does not culture the puny ones you pick with chopsticks in fried oyster dishes. No, sir. He rears the jumbo ones that you slurp in and masticate raw with squirts of lemon and dashes of Tabasco sauce.

Oyster culturing is still in its infancy in Malaysia. There were 344 culturists in Sabah as of 2013, but nearly all of them rear pearl oysters for the sake of the gems and the meat is just the secondary product.

“I rear two varieties – slipper and tropical oysters, which are the species served raw in restaurants,” says the former fisherman.

He grows them till they are about 9cm to 10cm long; this takes between nine and 12 months depending on the weather. His monthly harvest is between 1,000 and 3,000 oysters.

“I buy oyster seeds that are the size of a 10 sen coin each. They are vulnerable at that stage. Crabs can break through their shells and eat them, so I check the cages every day,” he says.

USM postgraduate student Poi Khoy Yen taking a dissolved oxygen reading at the farm.

USM postgraduate student Poi Khoy Yen taking a dissolved oxygen reading at the farm.

The seed supply is what makes it possible for Mohd Ridzwan to culture this delectable shellfish on a viable scale. The oyster hatchery is in Balik Pulau, Penang, and it is one of only two in South-East Asia.

“The other one is in Vietnam. We started the hatchery in 2009 and transferred our knowledge to farmers with research funding from Universiti Sains Malaysia, the Science, Technology and Innovation Ministry and the Ministry of Higher Education,” says USM’s marine ecologist Assoc Prof Dr Aileen Tan, who began her research in 1989. All of Mohd Ridzwan’s know-how comes from Dr Tan and her team.

“Eat a dozen of them and you only get about a quarter of the cholesterol in an egg yolk. Doctors in developed countries recommend it to their heart patients as a satisfying protein source to replace red meat,” she says.

Tourists occasionally find their way to Mohd Ridzwan’s floating farm through off-the-beaten-track tour packages.

“Only five to eight tourists visit a month but nearly all who come are oyster lovers,” he says.

Mohd Ridzwan (holding plate) has learnt to serve freshly harvested raw oysters to tourists and conservation volunteers who visit his farm. Here, volunteers (from left) Eryzal, Michael Curtis, Ahmad Fadzil Izaharuddin (in hat), Rupert Shean and Pavel Bognar check out the produce.

Mohd Ridzwan (holding plate) has learnt to serve freshly harvested raw oysters to tourists and conservation volunteers who visit his farm. Here, volunteers (from left) Eryzal, Michael Curtis, Ahmad Fadzil Izaharuddin (in hat), Rupert Shean and Pavel Bognar check out the produce.

The farmer has learned to serve them on ice with lemon, Tabasco sauce, and even wasabi.

“When I was a child, I would row a sampan into the mangrove forest and collect oysters growing on the tree roots. We cooked them and I only found out later that people love to eat them raw.”

Mohd Ridzwan says Taiwanese tourists love them best and would eat more than 10 per person.

Unlike the milky white oysters served in restaurants that can be soft and gooey, the oysters fresh from Mohd Ridzwan’s farm are a whole other experience. The flesh has a yellowish tinge because of the tannin acid in the river water. The best part is the bite texture. The bite – when an oyster is truly fresh – should have a crispy snap to it, and these certainly have that. And after you get past the initial brine, their unique metallic flavour comes with a mildly sweet undernote.

A word of caution from Dr Tan though: Make sure you have robust gut flora before attempting this gastronomic exotica.

“Raw oysters served in fine restaurants usually go through a depuration process using sterilised seawater. That is why they always appear milky white.

(In this process, seafood is placed in a clean water environment for a while to allow impurities to be purged.)

“Eating them right after harvesting is a unique experience, but you might get an upset stomach if you are not used to eating … adventurously,” she grins.

The widest point near the river mouth of Sungai Merbok is 2.5km across. The floating oyster farm can be seen in the distance, marked by the red roofs.

The widest point near the river mouth of Sungai Merbok is 2.5km across. The floating oyster farm can be seen in the distance, marked by the red roofs.

Mohd Ridzwan also gets a small number of conservation volunteers from around the world who find out about him through the worldwide academic network.

“They want to see how we can use a mangrove river for aquaculture but without damaging it. They help me to agitate the cages of oysters dangling in the water. I also teach them how to sort their sizes and clean the cages.”

(The oysters are agitated regularly to stop them from fusing together.)

Dr Tan stresses that this is clean aquaculture that does not pollute the mangrove forest.

“The shellfish feed on the naturally available plankton in the river. We developed a simple culturing method that remote coastal or riverine villages such as this one can easily adopt to earn good incomes.”

A small group of conservation volunteers from around the world regularly visits oyster farmer Mohd Ridzwan Ishak, 45, (foreground left) to learn. Here, (from right) Michael Curtis, 21, and Pavel Bognar, 21, Abdul Azim Che Abdul Rahim, 31, Ahmad Fadzil Izaharuddin, 31, and Eryzal Zainal, 33, are helping the farmer to agitate the oyster cages to clean them and keep the oysters from fusing together at the floating farm on Sungai Merbok along the banks of Kampung Sungai Batu Besi, Bujang Valley, Kedah yesterday.

A small group of conservation volunteers from around the world regularly visits oyster farmer Mohd Ridzwan Ishak, 45, (foreground left) to learn. Here, (from right) Michael Curtis, 21, and Pavel Bognar, 21, Abdul Azim Che Abdul Rahim, 31, Ahmad Fadzil Izaharuddin, 31, and Eryzal Zainal, 33, are helping the farmer to agitate the oyster cages to clean them and keep the oysters from fusing together at the floating farm.

Besides showing tourists his farm, Mohd Ridzwan has also taken them on muddy excursions to plant mangrove tree seedlings at low tide and search for huge mud clams that are called lokan in Malay.

“In the last seven years, I have helped to take tourists and volunteers to plant about 60,000 mangrove tree seedlings in this forest.

“I want the Kedah Government to know that the mangrove forest of Sungai Merbok is precious to us. And it is possible for the ecotourism potential to be economically rewarding for a villager like me.

“But upriver, I know there are large shrimp farms. When they sanitise their ponds after a harvest, they use chemicals that might be harmful to our forest when washed downriver. I hope the government will protect this river and forest,” Mohd Ridzwan says.

In October, Kedah Mentri Besar Datuk Seri Mukhriz Mahathir announced that the state would apply to gazette this river and mangrove forest as a Unesco (United Nations Educational, Scientific and Cultural Organisation) world biosphere reserve.


To experience Mohd Ridzwan’s farm, call him at 019-513 0119.