Bringing crabs to fields for higher returns

Turning low-lying fields into a 'home' for field crabs

On a morning visit to Mr Le Huy Diep’s more-than-2ha field in Trung Chinh commune, Thanh Hoa, water from a nearby river quietly flows through small channels into the field. Beneath the old sedge clumps, small crab holes are scattered across the mud. Occasionally, a field crab crawls out to feed, but quickly retreats into the moss and weeds along the bank at the slightest sound.

As he calmly checked each field-crab trap, Mr Diep said with a gentle smile: 'These crabs may be small and timid, but if we know how to attract and keep them here, farmers can earn an income without much work.'

A former commune official, Mr Diep returned to farming after retiring in 2016, hoping to make the most of his hometown’s potential. More than 2 ha of low-lying rice fields in Thap Linh Village, in the former Hoang Giang Commune, lay beside the Hoang River and were known for poor yields. While many households were considering giving up farming the land, he boldly leased the land and set out to develop a farm combining crop and livestock production.

He went all in in raising buffalo and cattle and planting fruit trees, but none of these ventures proved effective. He lacked management experience, while the low-lying land remained waterlogged year-round. Yet those difficult years led to an important discovery: he noticed that field crabs thrived naturally along the water’s edge. They grew well and reproduced quickly where the water was clean, sediment was abundant, water flowed freely, and human activity was minimal.

One question kept troubling him: Field crabs fetch a good price at the market, but if people continue harvesting them from the wild on a large scale, their numbers will eventually decline. They may also leave as their natural habitat is disturbed. So he wondered: if he could recreate their natural habitat, would they come on their own and make the area their home?

He took the question to people everywhere. Some even laughed, finding the idea rather absurd. He came to realize that he was not really 'raising' field crabs, but restoring a near-natural ecosystem to attract them to settle there, rather than catching them one by one as others did.

Once he had his family’s support, Diep hired an excavator to dig several channels across the fields, connecting them directly to the Hoang river. These channels were not simply for carrying water in, they created a continuous flow and allowed wild field crabs to move into the fields. Along the banks, he preserved the old sedge patches and even planted more to help prevent erosion and give the crabs shelter.

He also shared that, old sedge roots, moss, algae and plankton around the plants provide a natural food source for field crabs. So his daily work is not feeding them, but clearing the channels, keeping the water flowing, checking water levels and minimizing disturbance to the habitat. Over time, more and more small crab holes began appearing along the channels. He knew the field crabs had truly chosen his fields as their new home.

The first field-crab harvest reached nearly 40 kg per sao (1 sao = 360 sq m), far exceeding his expectations. The large crabs not only brought him a good return but also silenced the early doubts and criticism. People began to admire him, with some even calling him the 'Field Crab King'.

Working along with wature, keeping resources sustainable

He said that keeping the field crabs in the area is difficult enough, but harvesting them without disrupting the population is even more challenging. Based on his experience, he never catches crabs during the breeding season, from February to April, even though this is when they are most abundant. Harvesting begins only from late April through July, after the breeding season has ended. For a sustainable harvest, some must always be left for the next season. If the crabs are overharvested, the operation could quickly repeat the mistakes of wild harvesting.

Another lesson he has learned is not to harvest on too large a scale, but only take enough each day to meet market demand. This keeps crab stocks stable, minimizes disturbance to the ecosystem, and ensures buyers have a steady supply of quality crabs. 

His family now harvests around 3 tonnes of field crabs a year. At VND 75,000-80,000 per kg, they generate nearly VND 200 million in revenue. He also earns additional income by leasing out rice fields to local farmers to grow sedge. Each crab season, traders come directly to his fields to buy. As wild field crabs become increasingly scarce, those from his fields remain meaty, well-sized and full of their distinctive flavor.

Beyond selling field crabs, he plans to invest in crab-paste processing and explore frozen crab products. In the longer term, he hopes to refine the production process and register the products under the One Commune One Product (OCOP) program, turning the humble local crab from a traditional food into a locally branded specialty.

In Mr Diep's words: ‘What pleases me most is seeing more people visit my fields to learn from this approach and explore how it could work in similar low-lying areas. Rather than forcing such land to grow crops, making use of its vegetation and natural conditions to raise native species can deliver better returns, protect biodiversity and reduce production costs.’

$ 1 = VND 26,380 - Source: Vietcombank.