With critical thinking, science and a 3-phase model, Nguyễn Thanh Thế achieves success.
Can Gio is situated around 40km away from Ho Chi Minh City, where shrimp farming is a leading economic activity. With diseases running rampant in the area, such as Enterocytozoon hepatopenaei (EHP) and early mortality syndrome (EMS) or acute hepatopancreatic necrosis disease (AHPND), several farmers have decided to call it a day. Meanwhile, successful ones continue farming and become buyers of farms that have ceased operations.
One such farmer is Nguyễn Thanh Thế, who has been farming vannamei shrimp over the last 15 years. During a visit in March with the team from Forte Biotech, he was celebrating a recent purchase of a neighbour’s farm. With this latest addition, he now has ten production ponds, four in the current farm and six in the new farm.
Thế, who studied information technology and was encouraged by his brother and sister-in-law to start a farm together, said that many of the successful farmers did not really learn aquaculture. “After almost 20 years in shrimp farming, all that is needed is critical thinking, logic, and passion. For each problem, science and logic are always there.”
Critical thinking and adherence to SOPs
“Each farm will have different problems and issues; success comes with finding the logic since the science is there already. There is not much that we can do with EHP. We need to continue farming, and so we must try to reduce costs.” While acquiring farms, his approach is to keep them manageable. EHP is everywhere. “But we have to continue to farm anyway.”
said Thế,
He manages EHP with his well-thought-out water treatment system. His farm has three reservoir ponds covering 3,000m2. Incoming water slowly moves around baffles, settling organic matter. In the final treatment pond, chlorine gas is added. In less than 2 days, the water can be used for the grow-out ponds. Cautious of the optimal water quality, Thế tests water parameters before beginning to channel water for the grow-out stage.
“This amount of technology is sufficient for us. Whatever technology a farmer needs, it should be around water treatment and quality. Regarding autofeeders, we need to reset them after the rains. We kill EHP spores by using lime to bring up the water pH to 9. My message is to learn to optimise first, or else technology will fail you,”
emphasised Thế.
At the farm, his staff are very disciplined and professional in following the standard operating procedures (SOPs). They have at their disposal assistance from their feed suppliers, as well as analysis of water parameters and disease pathogens. When Forte Biotech approached Thế with its on-site PCR tests, Thế became an advisor to the young startup team on requirements for farms in Vietnam.
“For each problem, I find that science and logic are always there,” says Farmer Nguyễn Thanh Thế
Absence of shared biosecurity
However, Thế also faces several challenges in his farming operations. In Can Gio, the high density of shrimp ponds
has led to water pollution, with EHP levels rising as infected farms discharge untreated water into the environment.
Another issue is biosecurity, where many farmers, including those nearby, still show negligence and weak implementation of preventive measures. In addition, the cost of water treatment has increased sharply compared to the time before EHP became widespread, and the expenses for preventive medicines have also added to the financial burden.
Managing EHP and Vibrios
Thế believes that algae acts as a carrier of EHP spores. Therefore, his first step is to thoroughly disinfect incoming
water using chlorine gas. Then, an artificial colourant, Marine Blue (Unity, Thailand), is added to the pond water
during the first 60 days to prevent algae blooms. Adding colourant to shrimp ponds is an age-old practice in Asian
farms, primarily aimed at improving water quality and controlling unwanted plant growth. This method helps
manage algae by reducing sunlight penetration with blue dyes, which limits photosynthesis and suppresses the growth of filamentous and blue-green algae that can disrupt pond ecosystems.
Furthermore, by shading the pond, the dye can help stabilise water temperature, which is beneficial for shrimp health. Thế says that this step helps to suppress the Vibrio population. His aim is to prevent shrimp from eating algae and developing Vibrio-linked diseases.
Thế is not afraid of Vibrio pathogens, as there are checks every 5 days for Vibrios. The farm monitors the CFU/mL levels of Vibrio. “I am more afraid of EHP.”
Another strategy is to exchange only 30-40% of the pond water. He gained most of his knowledge on shrimp farming with CPF Thailand. Today, he is working together with CP Vietnam. Recently, Thế innovated the shrimp toilet at the farm, which he installed 6 years ago.
matter. In the final treatment pond, chlorine gas is added.
A 3-phase model
From these four ponds, Thế harvests 20 tonnes. This is the result of a three-phase farming system: nursery, pregrow-
out, and grow-out. Thế has learnt from CP Vietnam on setting up a semi-closed nursery pond. Here, post larvae from Ninh Thuan and Vung Tau are stocked at 1500- 1800PL/m2 and are reared over 20 days. Subsequently, shrimp from one nursery pond are transferred to an outdoor pond for the first pre-grow-out stage. The stock is transferred to two ponds and subsequently to four grow-out ponds. The stocking density in the final grow out stage is 100PL/m2.
The final output is size 25/kg shrimp after 111 days of culture. The cost of production is VND110,000/kg (USD4.16), at a survival rate of 90%.
Marketing live shrimp At this farm, harvesting depends on the broker. Approximately 10 tonnes are harvested over four days. Each day, the broker delivers live shrimp to markets in Hanoi, where prices are much higher than in the local market, which hovers around VND230,000-240,000/kg (USD8.2-9.1).
