On spraying days, drain the water: the sourcing value of Thanh Hoa's rice-plus-shrimp

In Truong Van commune, Thanh Hoa province in the north-central region of Vietnam, a rotation that releases giant freshwater prawns at the base of the rice plants has started moving. It is an organic-oriented model organized by the province's agricultural extension center on nearly 3 ha, and the agriculture-and-environment paper Nong nghiep va Moi truong reported from the site on 24 July. What works in the design is that the use of pesticides is calculated backward not from ideals but from the rearing condition that "spray and the prawns die." For Japanese buyers who agonize each time over how far they can trust a region's reduced-pesticide labeling, this structure offers a clue that can be verified from outside the paperwork.

The place a producer born in 1960 came back to over 30 years

The one reported on is Ngo Khac Thao, of Truong Thanh hamlet, Truong Van commune. VnEconomy records him as born in 1960, while the original paper writes "nearly 70." When he lifts a scoop net beside more than 3 ha of paddy, giant freshwater prawns with long blue claws leap in the water. The economics paper VnEconomy relates that, after studying machine manufacturing and working in construction, he returned to his home village in 1996.

Mr. Thao is said to be the first person in this area to try giant freshwater prawns, bringing seed stock back from the south in 1998. The prawns themselves grew, but at the time he suspended it because the market did not know this product and he could not read where to sell it. It started moving again in early 2024, when he put 1,000 at his own expense into a pond and, over about 18 months, landed about 750 kg of marketable prawns. The province's agricultural extension center, seeing this result, placed a nearly-3-ha organic-oriented rice-plus-prawn rotation model with him and bundled in the search for sales channels, which is the current form.

To the original paper Mr. Thao said, "This prawn is temperamental, but once you understand its habits it actually takes little work," and he cited that it adapts well to the environment and feeds mainly on natural food, that disease is rare and the unit price is high, and that this method also improves the paddy's environment.

Even the procedure for spraying pesticide is decided by the prawns

The core of this rotation is that rice and prawns hold each other's survival conditions. The rice casts shade on the water surface to hold down the water temperature, and the prawns eat the insects in the paddy, their droppings coming back around to the rice. The constraint works in the opposite direction too. To raise the prawns properly, the rice side must cut pesticide use to the minimum, prioritize biological inputs and follow an organic-conforming production process, the original paper explains. The procedure is set even for cases where control is unavoidable. Only registered agents may be used; before spraying, the paddy's water is drained to evacuate the prawns into the surrounding ditches, and the water is returned several days later after the agent has broken down. The accurate picture is not complete pesticide-free farming but one where, from the start, both the agents that can be sprayed and the days on which they can be sprayed are narrowed down.

This sequence works for the sourcing side. Without asking the producer why he chose organic, whether the prawns come up properly every crop is enough to gauge how much the amount, type and timing of agents are constrained. It is close in thinking to Hai Phong's organic rice, which uses the ragworms living in the paddy as an indicator of agent use (The proof of zero pesticides is caught in the paddy: Vietnam's organic rice x ragworm double-cropping). This is not, however, proof of pesticide-free farming. Conformity with residue standards is settled by inspection and the organic label by certification, each of which still needs to be nailed down separately.

On disease, Mr. Thao also states, "I have never seen the giant freshwater prawn catch a major disease like other aquatic species." The management conditions the original paper lists include keeping the water pH at 7 to 8.2, allotting 15 to 20% of the field area to the surrounding ditches, and releasing the seed in April to May. Compared with high-density prawn ponds, it is a lighter operation in both equipment and agents.

750 kg and 3 ha: two numbers from different sources

As a profit guide, the original paper says that if well managed it breaks even at a survival rate of around 30%, and goes on to write that releasing about 10,000 seed yields, even after deducting expenses, a profit of over 100 million VND (about 620,000 yen) per crop. What needs care is that this premise of 10,000 seed and the reported 750 kg are separate matters. The 30% survival rate is a figure presented as the break-even line and is not directly connected to the breakdown of the over-100-million-VND amount. The 750 kg is the result of Mr. Thao's own trial running 1,000 head in 2024, and for the current model the extension center organized on nearly 3 ha, no harvest record has yet been made public. How many tonnes a year the 3 ha produces is left blank.

What serves as a guide instead is the operation in Quang Trung ward of the same Thanh Hoa province. The fisheries trade journal Thuy san Viet Nam carries figures of about 800 kg a year from 12,000 head on 5,300 sq m, and about 3 tonnes a year across roughly 20,000 sq m for a five-household cooperative. That works out to around 1.5 tonnes per ha per year. It is hard to think that the density-restrained, organic-oriented Truong Van would exceed this, so even within the same rice-plus-prawn there is a split in design philosophy.

How the local people and the industry take it

The producer Mr. Thao emphasizes the low hands-on burden more than the difficulty. Saying it is temperamental but easy once you know its habits is also the flip side of having a solid feel for the reproducibility of the technique.

The original paper explains that the Thanh Hoa agricultural extension center included in its role not only building the model but also searching for buyers for the product. Given that the 1998 attempt stopped for want of a sales channel, this amounts to the authorities themselves acknowledging that the bottleneck in this region is not production technology but the exit side.

On the operation of Tran Xuan Hanh, who leads a cooperative in Quang Trung ward of the same province, the fisheries trade journal reports that annual profit is 100 to 150 million VND (about 620,000 to 930,000 yen), 4 to 5 times the previous fish-plus-rice figure of 30 million VND a year (about 190,000 yen). The actual selling price in Quang Trung ward the journal records is 300,000 to 400,000 VND per kg, overlapping with the small-size price band the original paper gives. The upper limit of 500,000 to 600,000 VND/kg is a value confined to the large size of 3 to 5 per kg and is not the average for the whole region.

What Japanese sourcing can extract from this region

To state the conclusion first: this is not a region you go to buy the prawns themselves. Even the higher-density Quang Trung ward is at a scale of about 3 tonnes a year for a five-household cooperative, so a container-scale contract cannot be put together. The price, too, is a local market rate of about 3,090 to 3,700 yen per kg for large size and about 1,850 to 2,470 yen even below that (about 162 VND to the yen, as of July 2026), not at a level where it can be lined up against other regions as a frozen raw material.

What can be extracted is, rather, the field and rice that the prawns constrain. The area of 3 ha, small as a quantity of prawns, is a unit for a deal as rice. And that rice, precisely because the prawns must be kept alive in the same paddy, has a narrow range of usable agents from the start. Before poring over copies of certificates, asking whether the prawns come up every crop lets you grasp which way the field's operation is oriented. In the sense that it reduces the time spent on primary screening, this ties directly to sourcing practice.

One more point: do not break the sequence of fixing the exit design first. In Thanh Hoa province, tilapia farming that began on the premise that the contracting partner takes the entire volume (A 34-year-old who quit as a mechanic, toward full-purchase contract tilapia farming in Thanh Hoa) and three-stage shrimp farming that built scale on the coast (A former fisherman earns 12 billion dong a year: three-stage shrimp farming on the Thanh Hoa coast) are both in motion, and a pattern of deciding the buyer before deciding the scale is growing within the province. If rice-plus-prawn is put together in the same sequence, it can avoid repeating the 1998 suspension.

As a way into a deal, it becomes realistic to secure a small quantity of prawns as a sample while making the main contract on rice. Route the prawns to small-volume slots usable in a restaurant chain's seasonal menu or a department-store event, and take the part that needs volume in rice and processing raw materials. The region side also gains the benefit of a rice sales channel being attached while the prawn unit price is high.

Where this model stands within Vietnam's shrimp sector as a whole

Vietnam's nationwide shrimp farming area exceeds 750,000 ha, of which more than 200,000 ha use organic or ecology-oriented methods such as shrimp-plus-mangrove or shrimp-plus-rice, VnEconomy reported in November 2025. The mainstay, however, is the brackish water of the Mekong Delta, and the species lean toward black tiger and whiteleg shrimp. Truong Van, which pairs giant freshwater prawns with rice in the fresh water of the north-central region, stands outside this map.

Seen from the Japanese side, this positioning works for diversifying sourcing origins. The Fisheries Agency's Fisheries White Paper (FY2024 edition, based on the Ministry of Finance's 2024 trade statistics) lists India, Vietnam and Indonesia among the main countries from which Japan imports shrimp. Vietnam has long been a top supplier, but the content leans toward marine species. Scenes of Vietnamese freshwater giant freshwater prawns on Japan's sales floors are still few. If a north-central region is added here, it becomes a new card in the lineup of suppliers, high unit price though it may be.

That the province's agricultural extension center holds both the technology and the sales channel is also easy for the Japanese side to handle, in the sense that it unifies the negotiating counterpart. Regions that spare you the labor of going around individual farmers to check yields are still not many in the north and north-central region.

Practical information to secure before negotiation

The original paper, for its part, does not show the breakdown connecting the premise of 10,000 seed with the revenue figure of over 100 million VND per crop. Because working backward straightforwardly from the 3-to-5-per-kg unit price opens up a gap in the numbers, the proportion of individuals that grow to large size needs to be checked on site. Yield and size distribution become the first point of discussion when nailing down price in this region.

Summary

Truong Van's rice-plus-prawn is not a region that competes on volume. What you should buy is, rather, the field where the choice of agents is narrowed in order to keep the prawns alive, and the rice that rides on top of it. As the next move, you want to start by asking the Thanh Hoa agricultural extension center about the model's remaining area and the variety and quantity of the 2026 rice crop. Secure the prawns with a tasting during the site visit and a small-volume slot, and nail down the price only after actual measurements of size distribution are out. Since this is a species that takes 18 months to reach marketable size, making contact earlier works to your advantage.

References: Nông nghiệp và Môi trường／VnEconomy／Thủy sản Việt Nam／VnEconomy (shrimp industry)／Fisheries Agency, Fisheries White Paper