In Hai Hoa village, Quang Ninh province in northern Vietnam, a demonstration of switching no-longer-profitable shrimp ponds to land-pond farming of saltwater grouper (Vietnamese name ca song) has begun. Farmer Pham Ngoc Chien released 5,000 juvenile fish into a 5,000-square-meter pond and plans to raise them to 3.5 to 4 kg over two years before shipping. The choice of a 'land pond' rather than a cage floated at sea, and the idea of raising premium whitefish in surplus shrimp ponds, become material for rereading, through the eyes of a Japanese importer too, the procurement map of Vietnamese seafood that is buffeted by typhoon damage and price fluctuation.
5,000 grouper fry at 1 fish/m² in a 5,000-m² shrimp pond, aiming for 3 to 4 kg in two years
This model, advancing with the support of the Quang Ninh Province Agricultural Extension and Forest Protection Management Center, is low-density farming holding the density to one fish per square meter. According to the center, the fry, about 28 g when stocked, grew to about 25 cm in length and about 250 g in body weight after two months of rearing, and if all goes well reach 3.5 to 4 kg in about two years. The expected yield, calculated at an average of 3 kg, is said to be about 15 tonnes for the whole pond. All the figures are target values during the demonstration, and the final yield depends on future management of water temperature, feeding, and disease.
| Item | Demonstration-model values |
|---|---|
| Pond area | 5,000 m² (converted from an old shrimp pond) |
| Number stocked / density | 5,000 fish / 1 fish per m² |
| Body weight at stocking | About 28 g/fish |
| After two months | About 25 cm in length, about 250 g/fish |
| Rearing period | About two years |
| Target weight | 3.5 to 4 kg/fish |
| Expected yield | About 15 tonnes (assuming an average of 3 kg) |
Low density makes it easier to curb growth variation and disease chains, and it also looks like a design drawing on the lesson of past shrimp ponds wiped out by deteriorating water quality. In contrast to shrimp's high-turnover intensification, it is a setup that fattens a small number of fish over a long time and bets on a high-unit-price fish. Even within the same Quang Ninh province, the shrimp cooperative running 90-day shipments at 7 to 9 turnovers a year differs entirely in aim and time axis. Shrimp that earns through turnover and grouper that is grown slowly to earn through unit price line up as different uses of the same land.
Behind choosing a pond over a sea cage are the 2,637 aquaculture operations that Typhoon Yagi destroyed in 2024
Vietnam's grouper farming has originally been dominated by cages floated within bays. What thrust risk head-on at that conventional wisdom was Typhoon Yagi, which struck Quang Ninh province directly on September 7, 2024. According to the province's damage tally, about 2,637 aquaculture operations in the province suffered losses, and in the hardest-hit Van Don district alone, the equivalent of roughly 32,000 tonnes at harvest time was reported lost, with total damage exceeding 2.2 trillion dong. In the cages swept away, 4-to-5-kg grouper raised over several years, at about 1 million dong each (about ¥6,000 at a rough ¥1 ≈ 170 dong), were lost on the scale of tens of thousands of fish. Many of the stricken cages were the traditional type assembled from bamboo, wood, and styrofoam, with low resistance to the gale.
A land pond can be placed outside this risk of 'assets going to zero overnight.' An embanked pond is hard to sweep away structure and all even in a gale, and water intake, drainage, and temperature are easier to control. There is more than one answer to typhoon risk. In Khanh Hoa province, abandoning wooden rafts, sea-surface farming that switches to typhoon-resistant HDPE cages is advancing. The path of staying at sea and making equipment sturdy, and the path of retreating from sea to land in the first place. What Chien in Quang Ninh chose is the latter, and the surplus shrimp pond became its receptacle.
Struggling shrimp and idle assets: the profitability gap that grouper conversion tries to fill
Shrimp ponds tend to be left idle when earnings fall due to disease or declining soil fertility from continuous cropping. A pond with salt remaining is hard to convert to other crops, and the idled asset remains as a farmer's debt. Grouper, a saltwater fish, is one of the few options that can instead use that salt-remaining pond as a resource. Rather than rebuilding, it makes use of the existing pond and water as is and swaps in a high-unit-price fish. Herein lies the appeal of the conversion.
The move to switch low-profit land to another high-value-added item is happening simultaneously in many parts of Vietnam. In Hue province, a lagoon's co-culturing five species in one pond for annual sales of 15 billion dong farmers are achieving this, and the question of how to remake an idled water surface and put it on a profitable footing is common. Quang Ninh's single-species, low-density grouper and Hue's multi-species co-culture are contrasting, but both are continuous in the thinking of 'not letting an empty pond sleep.'
Bui Huu Son of the Quang Ninh Agricultural Promotion Center explains that the aim of this model is to make productive use of low-performing shrimp ponds, restore the environment, and diversify production. Rather than a one-off success story, it is being demonstrated as a template that neighboring farmers facing the same problems can replicate, which gives it the potential to lift the whole production area.
Seen from Japan's premium white-fish market, grouper becomes a target for diversifying supply sources
In Japan's seafood market, grouper is a white-fish species that trades at high prices. The kue (longtooth grouper) of the same family is known as an ultra-premium fish; wild-caught specimens normally fetch around 10,000 yen per kg, and at year-end the market can top 15,000 yen. Farmed grouper, of course, sits in a far more affordable price band and cannot be placed on the same footing as wild kue served at high-end restaurants. Even so, the fact remains that this is a market with steady demand for premium white fish.
Vietnam is one of Japan's leading seafood sourcing partners, and high-value fish such as grouper, cobia, barramundi, and snapper have been exported targeting the premium markets of Japan, Hong Kong, and Singapore. For Japanese importers, a production area that relies solely on offshore cages means a risk that supply is cut off each time a typhoon hits. If an alternative route of land-based ponds is added to the production area, there is room to diversify sourcing even when bad weather sends prices swinging. Quang Ninh's 5,000 fish are still at the experimental stage, but the picture of "the land ponds survive even if the cages are wiped out" is a point that buyers who place weight on supply stability cannot overlook.
For land-pond grouper to make it into sourcing for Japan, the walls of volume, year-round availability, and traceability remain
That said, the distance from experiment to export commodity is not short. First, volume. At 5,000 fish and about 15 tonnes per pond, it does not reach a commercial lot, and stable supply cannot be discussed unless multiple farms spread the same template out into a broad base. Second, year-round availability. A one-off shipment on a two-year cycle struggles to meet the orders of buyers who want to draw supply all year. Simultaneous operation of multiple ponds with staggered stocking times is needed. Third, traceability and certification. Premium white fish for Japan only reaches the shelf once rearing records, antibiotic-use logs, and water-quality data are all in place.
Turned around, these are also issues that can be filled in by design on the production side. Low-density aquaculture inherently makes it easier to reduce reliance on chemicals and pairs well with record-keeping. What Japanese sourcing managers can do now is not to wait for a finished commodity, but to get an early read on which production areas such conversion models are emerging in and under what management systems. The move by production areas to extend their catchment from sea to land is advancing quietly ahead of the next typhoon season.
Sources referenced
- Nong nghiep va Moi truong — Farming grouper by using low-performing shrimp ponds (Quang Ninh Province)
- Nhan Dan Online — After Typhoon Yagi, aquaculture in Quang Ninh Province recovers step by step
- Responsible Seafood Advocate — Aquaculture in Vietnam (grouper and other exports to premium markets in Japan and Asia)
- Suisan Navi — List of white-fish species (price bands for grouper and kue)
