Mixing five species in one pond for 15 billion dong in annual sales: can Hue's lagoon aquaculture be bought?

On the lagoon shore of Phu Duong commune in Hue, central Vietnam, a farmer who keeps five species together across 30 aquaculture ponds, whiteleg shrimp, black tiger prawn, orange-spotted spinefoot, spotted scat and crab, is earning annual sales of 15 billion VND (about JPY 93 million at about 162 VND per JPY 1, as of July 2026). The local paper Nong nghiep va Moi truong reported this on July 24, 2026. For Japanese procurement staff who have watched single-species intensive aquaculture collapse over a single disease, this polyculture design changes how one reads regional risk. However, the fish he raises barely exist in Japanese retail. Even so, the worth of following this one farm is confirmed from the figures.

30 ponds, 135 tonnes a year: a polyculture operation born on Hue's lagoon

What Truong Ngoc Nhat (born 1974) inherited from his parents was a 0.3-hectare pond. Even after returning from military service, disease and low yields continued, and he once moved to upland farming in the Central Highlands. The turning point, at the end of 2005, was joining the polyculture model that the local agricultural extension center (Trung tam Khuyen nong) brought in, the paper reports. It is a design combining whiteleg shrimp and black tiger prawn with orange-spotted spinefoot (ca dia / scientific name Siganus guttatus), spotted scat (ca nau) and crab.

Twenty years on, there are now 30 ponds. At 2,500-3,000 square meters each, a simple multiplication gives 7.5-9 hectares. With two crops a year, he lands 100 tonnes of orange-spotted spinefoot, 14 tonnes of spotted scat, 14 tonnes of shrimp and 7 tonnes of crab, 135 tonnes in total. Sales are said to exceed 15 billion VND, and profit after deducting the investment is 2-3 billion VND (about JPY 12.3-18.5 million). He also doubles as a dealer in seedstock and aquaculture supplies, and this Profit brings in over 350 million VND a year (about JPY 2.2 million). Permanent employment numbers 15-20 people.

On a lagoon where monoculture collapsed, why did mixing survive

Tam Giang-Cau Hai is one of Vietnam's largest brackish lagoons, and Hue's aquaculture concentrates here. The 0.3-hectare pond Nhat inherited from his parents, too, could not support the household because of continuing disease and low yields, the source article writes. As long as it runs on a single species, a single outbreak loses an entire pond.

That said, this is not to say polyculture is a cure-all. The seafood trade journal Thuy san Viet Nam writes from the opposite angle: its assessment is that orange-spotted spinefoot has been handled mainly in polyculture, so its output has not grown and no dedicated farming area has formed. Polyculture is not a method that maximizes yield.

Even so, Nhat's ponds keep running because he can crush the downside. Even if one species falls, the remaining four stay, so he avoids years when income goes to zero. The ceiling on yield falls short of monoculture, but the floor in a bad year is shallow. In terms of regional selection, it is a type that rises in rank when sorted by worst case rather than by average.

Figures that could be verified, and figures that split on cross-checking

This is where regional evaluation gets tricky. Even for the same farmer, the figures differ by the outlet reporting them. Lining up the Dan Viet paper of November 2024 and the source article of July 2026, the outlines diverge.

The totals differ because the 2024 version adds in the supplies business's sales of 12 billion VND, whereas the 2026 version gives only a profit of over 350 million VND for the supplies business. Even for the same 'dealer,' whether sales or profit is written changes the order of magnitude. A swap in fish species (mullet or spotted scat) can also happen over two years. The near-doubling of orange-spotted spinefoot from 54 tonnes to 100 tonnes, however, leaves open the possibility that one of the figures is an approximation. What the Japanese side can use with confidence is only the skeleton common to both papers: 26-30 ponds, permanent employment of around 15, and supplies provided to nearly 200 households in all. Copying figures outside this into a proposal will trip you up at an on-site audit.

Even dividing back using only the common part, the shape of the business is visible. Dividing 15 billion VND by 135 tonnes gives an average unit price of about 111,000 VND per kilogram (about JPY 690). Dividing by area gives sales of about JPY 10.3-12.3 million per hectare.

Evaluation from three directions: government, regional brand and export statistics

The first is the government's evaluation. In 2024 the Central Committee of the Vietnam Farmers' Union selected Nhat as an 'Outstanding Vietnamese Farmer (Nong dan Viet Nam xuat sac).' It takes the form of an individual honor, but it strongly bears the color of being held up as the culmination of the polyculture model the locality backs.

The second is the regional-brand side. Thua Thien Hue province (at the time) advanced an application for a collective trademark, 'Ca dia Tam Giang - Hue - Dac san dam pha,' for its mainstay orange-spotted spinefoot, and in June 2024 the National Office of Intellectual Property accepted the application and published it in the industrial property gazette. The business report states that the registration certificate is scheduled to be issued in March 2025. Application acceptance and registration are different things, so if you write it in a proposal you should include the stage as well. The extension center has also been working out seedstock production technology, publishing a demonstration in which 20 fish per square meter were released into a 6,000-square-meter nursery pond to obtain fry of 5-7 centimeters at a survival rate of 50.75%. For market fish, 3 per square meter averaged 209 grams at a survival rate of 60.5% and 3.79 tonnes per hectare. It is at a stage where a path out of reliance on wild fry is beginning to take shape.

The third is the temperature gap that export statistics show. According to VASEP (the Vietnam Association of Seafood Exporters and Producers), seafood exports in the first half of 2026 were about US$5.8 billion, up 12.8% year on year. By market, China and Hong Kong grew to US$1.5 billion, up 37.9%, while Japan stayed at US$787.5 million, up 0.7%. The structure in which China has turned into the largest buyer is already in motion (China overtakes the US as Vietnamese seafood's largest market—how should Japan's sourcing, now third, move?), and Hue's lagoon product is no exception.

What Japanese procurement should buy is not the fish but the function of bundling

To put it honestly, there is almost no route to bring the fish caught in Nhat's ponds into Japan. Orange-spotted spinefoot and spotted scat have no fixed place on Japanese shelves, and at an annual scale in the low hundreds of tonnes they are hard to fit into a trading house's container plan. Nor is it a distance that can be shipped fresh.

What should be looked at is elsewhere. Every year, to nearly 200 households in all, he supplies materials and seedstock worth 50 million to 100 million VND per household (about JPY 310,000-620,000) on deferred payment. A simple multiplication gives 10-20 billion VND (about JPY 62 million-123 million). By calculation, he is running credit worth 3 to 10 times his own annual profit (2-3 billion VND) in the form of post-harvest settlement. What Japanese buyers find hardest to obtain in a Vietnamese producing region is neither the fish nor the price, but this person who can align 200 households to a single specification.

A person who holds the supply source of seedstock and feed is in a position to effectively decide the stocking date, density, feed brand and harvest size. Traceability and records of drug use, too, come together once this one point is held. In Cam Ranh, Khanh Hoa province, too, a farmers' club of the same kind has functioned as the core of collection (Aquaculture × tourism for 1 billion VND a year: how Cam Ranh's Billionaire Farmers Club earns its money). That Nhat served as vice-chair of the production and management farmers' club in Phu Vang district is the same kind of role. The partner the Japanese side should team up with is, not infrequently, the individual assembling lots upstream rather than the processing plant with an export record.

Turned around, risk, too, concentrates at a single point. In a region where the bearer of credit is one person, collection stops in the year that one person goes down. In negotiations, before annual sales, you should ask about the collection record on deferred-payment receivables and about the replacement for when he drops out.

The certification and processing homework polyculture poses

Polyculture also has a weakness in procurement. A state of five species in one pond does not mesh with aquaculture certification, which has been built species by species. The ASC (Aquaculture Stewardship Council) is consolidating its 12 species-specific standards into a single ASC Farm Standard, having indicated that it will publish the fully revised version v1.1 on November 1, 2026, and invalidate the species-specific standards from audits beginning on or after May 1, 2028. How small-scale aquaculture that handles multiple species in the same pond is positioned during this transition period will directly sway the export potential of regions like Hue. In marine aquaculture, the creation of national standards has gone ahead (Vietnam's first national standard for marine aquaculture, a move to break down the walls of insurance and financing), and whether lagoon polyculture can join that flow becomes the dividing point.

The other homework is the absence of processing. What grew in VASEP's first-half statistics were crab and crustaceans (US$206.2 million, up 26.2%) and squid and octopus (US$380.2 million, up 18.8%), both items to which value can be added through freezing or cooking. If the 7 tonnes of crab that Hue's polyculture produces cross the border alive, neither processing technology nor equipment remains in the producing region. Of the lagoon's five species, the ones with room to mesh with Japanese demand are crab, and the small fish that can be diverted into seasoning extract or feed raw material.

Practical information to grasp before approaching the Hue region

Leaving the unit price blank is deliberate. The retail price of lagoon orange-spotted spinefoot swings widely even within Vietnam, and no published materials on wholesale prices can be found. If you enter negotiations, obtaining the processing plant's FOB quote first is the quicker route.

Summary: look for the supplies dealer before the processing plant

What can be taken home from Hue's polyculture is not the fish themselves but how a producing region is assembled: the design of mixing five species to eliminate bad years, the collection that holds seedstock and feed to put 200 households on the same procedure, and the structure in which government supports it with trademarks and seedstock technology. With these three in place, it becomes a region that can get a specification through even with an empty export record.

The next moves can be narrowed to three. Choose one processing plant that handles Hue product and obtain FOB quotes for crab and shrimp. At the same table, ask whom that plant collects from and trace back to the individual circulating supplies and seedstock. On that basis, with an eye to the May 2028 ASC transition, inquire of a certification body how polyculture ponds will be treated in audits. Before buying the region, identify the person who bundles it. This order is, in the end, the faster one.

References: Nông nghiệp và Môi trường／Dân Việt／VietnamPlus (VASEP statistics)／Tạp chí Thủy sản Việt Nam／ASC International