{"id":1600,"date":"2026-10-06T13:00:00","date_gmt":"2026-10-06T04:00:00","guid":{"rendered":"https:\/\/vietnam-agri.com\/?post_type=industry_news&p=1600"},"modified":"2026-10-06T12:52:42","modified_gmt":"2026-10-06T03:52:42","slug":"bong-tuong-seed","status":"publish","type":"industry_news","link":"https:\/\/vietnam-agri.com\/en\/industry_news\/bong-tuong-seed\/","title":{"rendered":"A parent and child who established artificial breeding over 20 years; the barrier of 500,000 fish a month lies in the feed"},"content":{"rendered":"

On October 3, 2026, the Vietnamese fisheries outlet Tepbac ran the story of a father and son who have followed the seed production of marble goby (ca bong tuong, scientific name Oxyeleotris marmorata) for over 20 years. The father, Tam Tieu, mastered artificial breeding at his own farm in My Tho, former Tien Giang province (now Dong Thap province after the July 2025 reorganization), and the son, Nguyen Quoc Dat, raised the survival rate of larvae to 50-60 percent through rotifer feeding. They now ship 200,000-300,000 fish a month and aim for 500,000 a month. Even so, it remains a premium fish and has not become a large-scale farming target. The reason lies in the feed. It is stuck at almost the same place as the wall Japanese seed production faces.<\/p>\n

Getting them to hatch from eggs had been finished in the father's generation<\/h2>\n

The marble goby is the largest fish in the sleeper-goby family and is naturally distributed throughout Southeast Asia. Its flesh commands a high price, and the market accepts it. In southern China, since being introduced in the 1980s, technology from artificial breeding to seed rearing has accumulated, and it has taken hold as a high-value-added farmed fish. In Vietnam, Malaysia, and Thailand it is farmed in reservoir and river pens, or in ponds. It is a fish with the groundwork in place.<\/p>\n

Even so, for Mekong Delta farmers, this fish was long tied to wild seed. It fetches a price, but the volume coming in cannot be read. With the most important entrance left to nature, it does not become large-scale farming. It was under these circumstances that Tam Tieu entered the seed business. Over many years he made breeding something he could run himself and built up the production process for marble goby at the family farm. He is a figure who made achievements in seed production and ornamental fish in My Tho, Tepbac writes.<\/p>\n

But here a paradox emerged. He could hatch many, yet the number surviving to seed size was a separate matter.<\/p>\n

Life and death are decided in the few days when the fish is smallest<\/h2>\n

A marble goby just after hatching is very small, weak at catching food, and sensitive to environmental fluctuations. If the feed does not suit it or the water suddenly worsens during this period, the mortality rate jumps. According to Tepbac, this is not one seed farm's problem but a point that research on this fish has long noted. The high mortality of larvae and the slow growth of the seed. These two have blocked large-scale seed production. There is also a study that recorded it taking nearly a year to grow from 5 grams to 50 grams.<\/p>\n

Dat studied aquaculture at the Ho Chi Minh City University of Agriculture and Forestry and was involved in the manufacture and sale of animal and aquaculture drugs. As he went around farming areas, he noticed that solutions always came out only after the fish got sick, after the environment worsened, after damage began to appear. Returning to the family farm, he turned his attention to the stage before that, especially the period when the fish is still very small.<\/p>\n

The core of the change was the introduction of rotifers (luan trung). Rotifers are small-bodied and slow-moving, matching the predatory ability of early larvae. In a study Tepbac cited, a rearing process using rotifers and Artemia recorded a stocking density of 15 fish\/liter and a survival rate of 42 percent after 30 days. The survival rate at Dat's farm when using rotifers is currently about 50-60 percent.<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Item<\/th>\nDetails<\/th>\n<\/tr>\n<\/thead>\n
Target fish<\/td>\nmarble goby (ca bong tuong \/ Oxyeleotris marmorata)<\/td>\n<\/tr>\n
Location<\/td>\na family-run seed farm in My Tho, former Tien Giang province (now Dong Thap province)<\/td>\n<\/tr>\n
Larval survival rate<\/td>\nabout 50-60% (with rotifer feeding)<\/td>\n<\/tr>\n
Reference value (study)<\/td>\nrotifers + Artemia, 15 fish\/L, 42% survival after 30 days<\/td>\n<\/tr>\n
Current production volume<\/td>\n200,000-300,000 fish a month<\/td>\n<\/tr>\n
Goal<\/td>\n500,000 fish a month<\/td>\n<\/tr>\n
Shipping size (current)<\/td>\n3\u301c4cm\u30014\u301c5cm\u30015\u301c6cm<\/td>\n<\/tr>\n
Shipping size (to be added)<\/td>\n6\u301c7cm\u30018\u301c10cm\u300110\u301c12cm<\/td>\n<\/tr>\n
Unresolved challenge<\/td>\nSwitching from live feed to formulated feed<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

The survival-rate figure matters not because it produces a good-looking record. When the proportion that survives rises and stabilizes, the ceiling on the number of seed that can be put on the market shifts. Tepbac writes the improvement in survival rate and the current production of 200,000-300,000 fish a month in sequence, but it does not write that production was decided by rotifers alone. The number of broodstock, the scale of the facility, and labor all matter just as much.<\/p>\n

The bigger the seed is grown before sale, the more risk the seed farm takes on<\/h2>\n

The current shipping sizes are three tiers-3-4 cm, 4-5 cm, 5-6 cm-and in future they plan to add 6-7 cm, 8-10 cm, and 10-12 cm. It looks like a story of a lineup extended by just a few centimeters, but the substance is a reassignment of profit and loss.<\/p>\n

The smaller the seed, the more the remaining risk shifts to the farmer's side. The buyer does the intermediate rearing, sorts by size, manages the water, and takes on die-offs until the fish grows large enough. If the seed farm keeps them in hand longer and sells at a larger size, that risk stays with the side with rearing facilities in place. The farmer can receive larger fish, but the seed farm additionally bears feed cost, area, time, and the danger of die-offs.<\/p>\n

And here, this fish's old weakness returns. The feed.<\/p>\n

A pricey fish, yet chasing live feed every day<\/h2>\n

The marble goby is a predatory fish. Its main food in the wild is small shrimp, small fish, and benthic organisms, and a study at Vietnam's Tri An Lake (ho Tri An) recorded small freshwater shrimp as the most important food component. In an environment rich in natural food this is a strength, but brought into mass production it becomes a shackle.<\/p>\n

With a few ponds, a farmer can procure fish and shrimp for feed. But once the head count reaches hundreds of thousands, the question changes from 'will the fish eat it' to 'can you supply that feed every day at the same quality and price.' Live feed has one more troublesome point: it is hard to grasp how much the fish actually ate. If you record the weight put in, the calculation itself is possible, but because live feed is not constant in moisture or leftovers, the feed conversion ratio (FCR) is hard to produce. If how much feed it took to make one kilo of fish stays vague, you cannot compare the previous crop and the next crop with the same yardstick.<\/p>\n

Dat has begun trying to wean them onto formulated feed. This is what decides the next stage. The marble goby is known for the difficulty of switching from live feed to formulated feed, and international research too sees this transition period as one of this fish's major obstacles. The fish tend to reject pellets, and mortality rises during the switch.<\/p>\n

So the problem is not making a pellet with enough protein. It is getting the fish to eat it. The attracting smell, the hardness, the grain size, the timing of the switch, and the predatory habits all become variables to test. Some individuals accept it first, while others keep waiting for live feed. Rush and they stop eating; drag out live feed too long and the original constraint stays as is.<\/p>\n

Fully farmed glass eels at 10,000 a year, this fish at 200,000 a month-for both, feed design decides the scale<\/h2>\n

The point of interest for Japanese readers is that this story has almost the same structure as eel.<\/p>\n

On May 20, 2026, the Japan Fisheries Research and Education Agency, jointly with Yamada Suisan and Marino-Forum 21, announced a trial sale of kabayaki from fully farmed eel. It is said to be the world's first case of kabayaki from fully farmed eel. Yamada Suisan has, since fiscal 2024, succeeded for two consecutive years in producing over 10,000 fully farmed glass eels a year at an efficiency comparable to the Agency. What has long been the wall for eel too was the feed and survival rate in the larval period.<\/p>\n

The orders of magnitude differ greatly. A Vietnamese family-run seed farm puts out 200,000-300,000 fish a month, while a Japanese national project and company produce 10,000 a year. Of course the fish species and difficulty are entirely different. What is the same is that for both, 'what feed to give and when' decides the survival rate, and that survival rate directly decides the scale of the business. Rotifers are a staple of initial feed in Japanese seed production too, and the tool the Vietnamese seed farm arrived at was the same.<\/p>\n

There is one more view the Japanese side can use in practice. When buying Vietnamese farmed fish, asking the two questions 'is the seed artificial or wild' and 'is it raised on formulated feed' gives material for gauging how readable the supply is. If the seed depends on the wild, volume swings by year; if it is centered on live feed, the basis for the cost is hard to produce. tilapia, whose exports to Japan grew 77% in eight months<\/a> and pangasius are fish species that have these two in place. That said, these are not the only reasons volume comes out. Containing disease, the processing plant's setup, transport, and pull from the demand side all matter just as much.<\/p>\n

Even when feed-plant certification is in place, fish that do not eat that feed remain<\/h2>\n

The upstream of Vietnam's aquaculture feed has become quite well-ordered over these past few years. Vietnam has the world's most ASC-feed-certified plants, at 15<\/a> reaching, and in Ca Mau, CP's feed plant began operating<\/a>. Both certification and equipment are coming into place. Even so, the marble goby is not riding on that feed. The fish does not move on the idea of a general-purpose pellet that suits any fish, and research has continued to point out that no feed designed specifically for it exists. The maturation of the feed industry and the scaling-up of individual fish species advance on different clocks.<\/p>\n

Price swings are also real. Tepbac also carries an article headlined 'Ca Mau: Gia ca bong tuong giam, nguoi nuoi mat hang chuc ty dong' (Ca Mau: the price of marble goby falls, and farmers lose tens of ty dong = tens of billions of dong). Being a premium fish does not mean it is safe. Note that the same site's seed sales section lists 5-6 cm seed at 3,000 dong each (about 18 yen). At 300,000 fish a month, that is a revenue scale of 900 million dong (about 5.49 million yen).<\/p>\n

Over more than 20 years, the stages have advanced from wild seed to artificial breeding, from mass larval die-offs to a 50-60 percent survival rate with rotifers, and from small seed to large seed. Tepbac's article closes with the phrasing, 'It is a journey of more than 20 years, but it has not yet reached its final destination.' In the single step from 300,000 to 500,000 fish a month, the weaknesses of the process are magnified. A 10-percent difference in survival rate becomes, at that point, a difference of tens of thousands of fish. A rearing period extended by several weeks means feed, area, labor, and danger all increase just as much.<\/p>\n

Listing what the buying side should ask<\/h2>\n\n\n\n\n\n\n\n\n\n\n
What to confirm<\/th>\nWhy ask it<\/th>\n<\/tr>\n<\/thead>\n
Is the seed artificial or wild<\/td>\nIf it depends on the wild, volume swings year to year<\/td>\n<\/tr>\n
What is the initial feed in the larval period<\/td>\nIf rotifers and the like are used, the survival rate tends to be stable<\/td>\n<\/tr>\n
Is it raised on formulated feed<\/td>\nWith live feed alone, neither FCR nor cost can be produced<\/td>\n<\/tr>\n
Can they produce an actual FCR figure<\/td>\nA partner who cannot produce figures cannot produce a basis for price negotiation either<\/td>\n<\/tr>\n
The increments of shipping size<\/td>\nThe larger the size you can buy, the more your own die-off risk is reduced<\/td>\n<\/tr>\n
The range of unit-price swings over the past two years<\/td>\nThe more premium the fish, the larger the downside phase<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Summary<\/h2>\n

In marble goby seed production, the father's generation solved 'how to make offspring,' and the son's generation advanced to 'how to repeat and multiply.' With rotifers the survival rate became 50-60 percent, and 200,000-300,000 fish a month began to come out. What lies ahead next is weaning onto formulated feed, and if this passes, the feeding amount can be measured, the growth rate becomes known, the FCR comes out, and the cost can be compared. However, Tepbac itself writes that the questions-what is a reasonable FCR to set, how far the farming period can be shortened, how far the cost per kilo can be lowered, and at what scale it is truly efficient-line up again after that.<\/p>\n

There is one thing Japanese fisheries people can do right away. If you are buying fish from Vietnam, or trying to, ask about that fish species 'is the seed artificial' and 'does it grow on formulated feed.' A fish species that returns 'yes' to both of these has readable price and volume. If even one is 'no,' that fish will not yet come down from the premium-fish shelf.<\/p>\n

The yen conversions in the text are calculated at 1 yen = 164 dong (the prevailing rate as of October 6, 2026).<\/p>\n

Sources<\/h2>\n