Giant freshwater prawns co-cultured in Thanh Hoa's paddies raise the value of the same land 1.5–3 times

Aquaculture that releases giant freshwater prawns (tom cang xanh) into rice paddies is lifting the value of the same land several-fold in Truong Van, Thanh Hoa province. The 24 July 2026 issue of Nong nghiep Moi truong (the agriculture-and-environment paper) reported this organic rice-plus-large-freshwater-prawn polyculture. Because it is grown pesticide-free, it does not rely on chemicals and it is easy to trace what was applied where. For sourcing and import buyers in Japan, the question is whether this production region becomes a candidate as a supplier of premium-tier freshwater prawns where traceability is demanded.

The rice shades the prawns, and the prawns eat pests and drop organic fertilizer

The central figure is Ngo Quac Thao, who farms in Truong Thanh village, Truong Van commune. Nearly 70, he is one of the pioneers who brought giant freshwater prawns to this area and has poured about 30 years into the species. The stage is more than three hectares of low-lying wetland paddy. The rice can suppress pests even without pesticides, and the prawns grow at low cost feeding on aquatic plants and plankton. The rice shades the prawns, and the prawns reduce natural enemies and supply organic fertilizer; this symbiosis forms the foundation of farming that works even without pesticides. By layering large freshwater prawns onto low-lying wetland that was prone to waterlogging and hard to earn from with rice alone, the same area yields two incomes, rice and prawns. The organic cultivation of rice and the prawn farming have become preconditions for each other, a design where you cannot carve out just one side.

Large prawns fetch 500,000 to 600,000 dong/kg, and releasing 10,000 gives profit of over 100 million dong

The yen conversions are rough estimates at an indicative rate (about 170 Vietnamese dong to the yen) and swing with the market. The prices, profit and survival rate all use the figures from the primary article as-is. Because feed costs little and disease is rare, it can be made profitable while lowering dependence on chemical inputs.

A pioneer of 30 years shows a form that takes hold even in low-lying wetland

Mr. Thao's 30 years show that this is not a passing fad but a form that is taking hold as one that can be sustained for the long term in low-lying wetland. On the technical side, the way rice and prawns complement each other to curb pesticide and feed costs is valued, and horizontal expansion to other low-lying wetlands is expected. In the same Thanh Hoa, there is also another rice-plus-prawn site that reconciles rice and prawns by draining the water on pesticide-spraying days to protect the prawns, and polyculture is spreading to several operators within the province. Mixing multiple species in a single pond to grow annual revenue, lagoon farming in Hue is one example; the idea of taking multiple incomes from a single body of water is becoming an undercurrent of Vietnamese aquaculture.

Pesticide-free and traceable works for small-volume premium-tier sourcing

In Japanese seafood sourcing, residues of antibiotics and chemicals in farmed shrimp have long been a concern. Freshwater prawns grown without pesticides through polyculture with rice can be an answer to that concern. In particular, being able to trace which paddy they were grown in and how is valuable to food-service and retail that demand traceability. At present, however, it is at a scale of three hectares and not at a stage where it can suddenly supply large lots for Japan on a stable basis. Export also carries separate hurdles: freezing and processing, hygiene management such as HACCP, and export permits.

The level at which large prawns (3 to 5 per kg) trade locally at 500,000 to 600,000 dong, around 3,000 yen in yen terms, meshes with Japan's high-value-added tier if the story of pesticide-free and freshwater is attached. But this is the price traded locally while the prawns are still alive, and once freezing, processing, transport and tariffs are added the retail price changes greatly. Rather than judging by a simple cost comparison, you want to see whether it can be turned into a product together with its backstory of "pesticide-free, traceable, low-lying-wetland organic polyculture." The more a buyer has a sales floor that can turn a story into a price, the more it can draw out this region's value. Conversely, sourcing that seeks only bulk cheapness will not mesh with this small-scale region from the start.

Get involved in designing hygiene management and environmental proof before the volume is in place

Truong Van's rice-plus-prawn polyculture is a case that turned low-lying wetland into a pesticide-free freshwater prawn region and multiplied the value of the same land. For the Japanese sourcing side, it is not a partner you can buy large lots from now. But its character of pesticide-free, low-input and traceable makes it a candidate for premium-tier freshwater prawns and environmentally conscious sourcing. Just as, in Ca Mau, the EU and an NGO spent 42 months growing "low-emission shrimp" into proof for sourcing, Measure the flow in which environmental value turns into sourcing creditworthiness is advancing in seafood too. The move to make is to build a relationship with the region while it is still small and get involved early in designing hygiene management and environmental proof. If you move only after the volume is in place, the good regions will already be locked up by other buyers.

Sources

Nong nghiep Moi truong, "The prawns embrace the rice, value doubles" (24 July 2026)
Nhan Dan, "Giant freshwater prawn farming in organic rice paddies"
VnEconomy, "Turning low-lying wetland into a gold vein with rice plus freshwater prawns"