Pangasius nursery protocol with Than Vuong products: from fry to harvest at 30 fish/kg

In short: Pangasius fry are raised in the nursery pond from stocking until fingerlings are harvested at 30 fish/kg, with no transfer to a second pond to grow on. The first 25 days follow the Than Vuong Technical Department nursery protocol: grow natural food, mild disinfection, tail-rot prevention. At the end of week 4 the fish are thinned out, then a routine is kept until harvest: disinfect the water and re-seed probiotics 24–48 hours later; check for parasites and deworm when needed; mix probiotics, vitamins and liver support into the feed. In the 7–10 days before harvest, preparation steps keep the fish healthy and cut losses in transport.

500–1,000 fry/m²

fry stocking density

30 fish/kg

fingerling harvest size

24–48 hours

to re-seed probiotics after each disinfection

Eight-step Pangasius nursery diagram: pond preparation, stocking fry, days 1–10, days 11–19, thinning, routine care, preparing for harvest, sale at 30 fish/kg — The whole protocol in one figure; doses for each product are in the sections below. Thumbnails: step 1 Khả Vân Đại Hãn (CC BY-SA 4.0), step 2 Bùi Thụy Đào Nguyên (CC BY-SA 3.0), step 3 Dmitry Kulakov (CC BY 4.0), step 7 U.S. Fish and Wildlife Service (public domain); steps 4, 5, 6, 8 Than Vuong photos.

1Pond preparation

Disinfect the bottom, lime, filter water, disinfect and grow Moina before stocking.

A nursery pond needs a reliable, clean water supply that is easy to fill and drain. The bottom soil should be free of acid sulphate and salt, with firm dykes that hold water. Keep the surroundings open, with few trees shading the water, and make sure there is easy access for bringing in fingerlings, feed and supplies.

Earthen pond in Chau Phu, An Giang — Earthen pond in Khanh Hoa commune, Chau Phu district, An Giang, Vietnam (February 2023). Photo: Khả Vân Đại Hãn, CC BY-SA 4.0, Wikimedia Commons.

Before filling

Drain, remove sludge, disinfect the bottom

Drain the pond, remove bottom sludge and clean the dykes. Once the bottom has dried, disinfect it; spread lime the next day.

WORK 801 kg/800 m² of pond bottomThan Vuong nursery protocol dose

Copper sulphate1 kg/1,000 m²common input

Lime5–7 kg/100 m², spread the next day

When filling

Filter the water carefully

Fill through a fine mesh filter to keep out wild fish, frog eggs and predators.

After filling · day 1

Disinfect the water

Apply at 9 a.m. once the pond is full.

BKC GOLD1 kg/1,000 m³

After filling · day 2

Minerals and natural food (Moina)

Apply FYTO FLOC together with GROWMIN. Ferment NIAZYME with powder feed in 50–60 litres of water and scoop the mixture into a bucket for each application.

FYTO FLOC3–5 kg/1,000 m³

GROWMIN1 kg/1,000 m³Than Vuong nursery protocol dose

NIAZYME1 kg fermented with 5 kg powder feed

When stocking fry, pond water should be: pH 7–8 · temperature 28–30 °C · dissolved oxygen at least 3 mg/L. Check NH₃ and NO₂ before stocking with the toxic gas calculator (select striped catfish).

2Selecting and stocking fry

Healthy, even-sized fry; 500–1,000 fry/m² stocked in cool hours; anti-stress afterwards.

Fish seed farm with net cages in a pond in Dong Thap — A fish seed farm with net cages set in a pond in Doc Binh Kieu commune, Thap Muoi district, Dong Thap, Vietnam. Photo: Bùi Thụy Đào Nguyên, CC BY-SA 3.0, Wikimedia Commons.

Fry source: a hatchery with clear origin and a quarantine certificate.
Healthy fry: uniform size, straight body, bright colour, no deformities; they swim fast and react well, with no signs of fungus or haemorrhage.
Density: 500–1,000 fry/m² (500,000–1,000,000 fry per 1,000 m² of pond).
Stocking: stock in cool hours; float the bags in the pond for 10–15 minutes to equalise temperature before opening them.

Right after stocking

Help fish recover from stress

MIXBOOM2 kg/1,000 m³ of waterlabel: after stocking

3The first 25 days: feed and water-treatment schedule

Feed by age, the 25-day water-treatment schedule and predator control.

Feed

First 2 weeks: fry eat Moina in the pond, plus soybean flour and egg yolk mixed with water and spread over the whole pond 5–6 times a day (FAO).
Days 11–15: switch gradually to powder feed with 35–40% protein, 4 meals a day (Ministry of Science and Technology).
From week 4: floating feed with 30–35% protein, 3 meals a day, pellet size matched to mouth size (Ministry of Science and Technology, FAO).
Spread feed slowly and evenly over the pond; feed just enough, leaving no uneaten feed to foul the water.

Moina under the microscope — *Moina macrocopa* under the microscope: a tiny crustacean and the live food of fry in the first 2 weeks. Photo: Dmitry Kulakov, CC BY 4.0, iNaturalist.

Water-treatment schedule for the first 25 days

Days 1–10

Keep Moina, stabilise the water

Apply daily for the first 2 days, then every other day. Goal: keep live food in the water, with clear water, good colour and stable pH and oxygen.

FYTO FLOC3–5 kg/1,000 m³

GROWMIN1 kg/1,000 m³

NIAZYME1 kg fermented with 5 kg powder feed

Days 11–15

Mild disinfection every other day

Apply AQUA DINE every other day, ideally after 6 p.m.; salt can be added.

AQUA DINE1 bottle/5,000–6,000 m³ of water

Salt20 kg/1,000 m³

Days 15, 17, 19

Tail-rot prevention

Treat in the morning. From day 17, raise the water level by 15 cm at each treatment. Re-seed probiotics 24–48 hours after each treatment.

WORK COP Plus1 bottle/5,000 m³ of water

POWER GLUTA1 bottle/5,000 m³ of water

MAX 40001 pack (250 g)/6,000–7,500 m³ of waterre-seed probiotics

From day 15

Start mixing into feed

Once fish take mixed feed well, add probiotics and beta-glucan to support digestion and resistance.

PRO F1 kg/tonne of feed, 1 meal a day, every 3–5 days; in cold weather or when digestion is poor: 2 kg/tonne

BETAGLUCAN GRO0.5–1 g/kg feed; when weather or water conditions change: 2–4 g/kg

Predator control

Predators have a large effect on fry survival: tadpoles, backswimmers, dragonfly nymphs, predatory fish and birds. From filling the pond until the end of the first 7 days after stocking, remove frog eggs and tadpoles every day. Filter water carefully, fence the pond with netting, and act as soon as you spot them.

Monitoring fish health

First week: every morning, check how fish swim and feed, and look for red spots on the body.
From week 2: check fish, water colour and feed intake every day so you can adjust in time.
From about day 20: each week, examine the skin and gills of 5–10 fish; if you find protozoa or flukes, treat as in section 5.

4From day 25 to harvest at 30 fish/kg

Thinning, routine care and daily checks until harvest.

At the end of week 4, thin out to 150–200 fish/m² (Ministry of Science and Technology, FAO). From then on, exchange water according to actual water quality and follow a routine until harvest:

Every 10 days

Disinfect the water, rotating products

Run aeration while applying. Apply AQUA DINE after 6 p.m.

POWER GLUTA1 bottle/5,000 m³ of waterevery 10–15 days

AQUA DINE1 bottle/5,000–6,000 m³ of waterevery 10 days

24–48 hours after disinfection

Re-seed probiotics

MAX 40001 pack (250 g)/6,000–7,500 m³ of water

NIAZYMEfingerling ponds that are hard to exchange or have a lot of bottom organic matter: 1 kg/8,000 m³ for 2–3 days in a row

Every 5–10 days

Minerals and toxic gases

GROWMIN1 kg/1,500–2,000 m³, every 5–7 days

YUCCA GRO1 kg/6,000 m³, every 10 days

YUCCA Cwhen NH₃ is high and fish gasp at the surface: 1 kg/2,000 m³

Routinely

Mixed into feed

After mixing, coat with ATOMIC Plus (for pellets, not for powder feed), air-dry for 20 minutes, then feed.

LIVER GRO2 g/kg feed

BIOZYME2 g/kg feed

QUICKSHELL GOLD2 ml/kg feed

BETAGLUCAN GRO2 g/kg feed

GRO C302 g/kg feed

Pangasius rising to floating pellets. Spread feed slowly and evenly across the pond so all fish get their share. Photo: Than Vuong archive.

Daily checks

Every morning, check whether fish crowd at the pond edge, how they swim and whether the bottom is dirty.
Remove weak and dead fish to check their exterior, organs and parasites; record losses every day.
Check 5–10 fish for parasites regularly, especially before and after deworming.

When losses rise

Losses rising for 2–3 days in a row: cut feed to 50–60% and dissect 5–10 fish. If losses have not fallen after 2–3 days: stop feeding, identify the disease and call Than Vuong technical support at +84 867 957 568 before using any drug.

5Preventing common diseases in Pangasius fingerlings

Parasites, water mould, tail rot, haemorrhage, bacillary necrosis: signs and prevention.

Use veterinary drugs only after the disease has been correctly identified, and only as indicated on the label. Doses and treatment steps are in Than Vuong's fish disease protocols.

Some disease signs in photos

Pangasius fingerling with water mould — Water mould: a Pangasius fingerling infected with *Saprolegnia* in a trial; the arrow marks fungal growth on the pectoral fin. Photo: Rathod et al., Scientific Reports 2024, CC BY 4.0.

Pangasius with white spots on internal organs — White spots on the internal organs of Pangasius farmed in the Mekong Delta (arrows); the fish showed no clear external signs. The researchers isolated *Edwardsiella tarda* from these fish. Photo: Ho et al., Applied and Environmental Microbiology 2026, CC BY 4.0.

Pangasius with haemorrhage around the eye and head — Haemorrhage around the eye and head (red circle) and at the base of the pectoral fin in Pangasius farmed in Bangladesh, suspected *Aeromonas* infection. Photo: Ferdousi et al., PLOS ONE 2025, CC BY 4.0.

Trichodina under the microscope — *Trichodina* in fish gill mucus at 400× magnification (a carp sample, shown to illustrate the parasite's shape). Photo: Dărăbuș et al., Microorganisms 2024, CC BY 4.0.

How to prevent each disease

External parasites

Trichodina, gill flukes

Signs: fish flash and startle while feeding, gather in small groups weaving through each other, lose a lot of mucus and feed poorly. Skin and gill checks show protozoa or flukes.

Prevention: filter water and remove wild fish thoroughly during pond preparation, stock at the right density and disinfect routinely. Fingerlings can be bathed in WORK COP Plus 3–5 g/m³ for 10–20 minutes.

If fish are already sick: External parasite protocol.

Internal parasites

Flukes and tapeworms in the gut and liver

Signs: fish pass loose, undigested faeces, feed poorly, grow slowly and vary in size; dissection shows parasites in the gut.

Prevention: check regularly, especially fish in older ponds.

If fish are already sick: AQUA PRAZI as labelled: mix 100 g into 20–30 kg of feed (equal to 100 g for 200–300 kg of fish) for 3–5 days in a row; stop feeding 1 day before deworming. After deworming, mix in BIOMAX 1 g/1.5 kg feed and AQUAMOS 1 kg/1,500–1,800 kg feed for 3–5 days. See the internal parasite protocol.

Water mould

Saprolegnia

Signs: white, cotton-like patches on the skin and fins; common in cold weather and when fish are injured.

Prevention: handle fish gently when seining; disinfect routinely with POWER GLUTA (1 bottle/5,000 m³ of water, every 10–15 days).

If fish are already sick: AQUA DINE 1 bottle/1,000–1,500 m³ of water (label: kills disease-causing fungi and bacteria); call technical support if it does not improve.

Tail rot, white body

Flavobacterium columnare bacteria

Signs: fish gather where water flows, swim sluggishly, produce excess mucus and lose skin colour; tails are eroded.

Prevention: follow the day 15, 17, 19 schedule in section 3; use clean intake water; check pH, NO₂ and H₂S regularly. See the tail-rot prevention article.

If fish are already sick: call Than Vuong technical support for advice based on your pond.

Haemorrhagic disease

Aeromonas and opportunistic bacteria

Signs: red fin bases and vent, haemorrhages on the skin. In Pangasius fingerlings about 25 days old, a red vent is the earliest sign.

Prevention: disinfect and re-seed probiotics routinely; keep the pond bottom clean and do not overfeed.

If fish are already sick: Haemorrhage protocol (OXYTETRA as indicated on the label).

Bacillary necrosis (BNP)

Edwardsiella ictaluri bacteria

Signs: fish are sluggish and stop eating; deaths are scattered at first, then rise quickly; dissection shows white pus spots on the liver, kidney and spleen. Outbreaks are common when water drops below 28 °C and in the rainy season.

Prevention: stock at the right density and keep the water clean; at the change of season, increase MAX LIVER and BETAGLUCAN GRO in the feed.

If fish are already sick: Bacillary necrosis protocol (FLOR-MAX, a drug for Pangasius and basa).

White liver, white gills

Multiple causes

Signs: pale liver and gills; poor appetite for a long time, slow growth; often in ponds that have had many courses of antibiotics.

Prevention: do not overuse antibiotics; deworm on time; give liver support routinely.

If fish are already sick: White liver, white gills protocol.

6Preparing for harvest and selling fingerlings

Condition, cut feed, stop feeding, gather and transport with few losses.

The goal is healthy fish at harvest that withstand seining and transport and suffer few losses when stocked into grow-out ponds.

7–10 days before

Check fish health and condition the fish

Review losses over recent days and dissect 5–10 fish. If fish show signs of disease, do not harvest yet.

VIMIX1 kg/300–500 kg feed

GRO C302–3 g/kg feed

MAX LIVER1–2 g/kg feed

Last 5 days

Cut feed, add anti-stress

Reduce feed by 5–10% each day.

VIMIX1 kg/300–500 kg feedstressed fingerlings

GRO C302–3 g/kg feed, 1 meal a day, preferably the midday or afternoon mealanti-stress

1–2 days before

Stop feeding, mild disinfection

Stop feeding 1–2 days before seining. Apply disinfectant the evening before.

AQUA DINE1 bottle/5,000–6,000 m³ of water

Harvest day

Gather and transport

Apply where fish are gathered in the net; handle gently to avoid abrasions. Add anti-stress products to the holding-tank or transport-boat water.

YUCCA C100 g/10–15 L of waterlabel: during harvesting

VIMIX5 g/100 L of holding-tank water during transport

GRO C301 g/10–20 L of water during transport

Seining fingerlings in the catch basin of a drained nursery pond (a hatchery in the United States). Work gently and quickly so fish suffer fewer abrasions. Photo: Sam Stukel, U.S. Fish and Wildlife Service, public domain, Wikimedia Commons.

Fingerlings leaving the pond must be free of bacillary necrosis. Harvest size is about 30 fish/kg (about 33 g each).

Quick answers

Why re-seed probiotics after disinfecting?

Disinfectants also kill the beneficial bacteria in the water. After 24–48 hours, once the disinfectant has worn off, re-seed with MAX 4000 or NIAZYME so beneficial bacteria keep breaking down waste and the water stays stable.

Should antibiotics be mixed into feed routinely to prevent disease in fingerlings?

No. Prevent disease through water management, probiotics, routine disinfection and stronger resistance through feed. Use veterinary drugs only after the disease has been identified, as indicated on the label and following the protocol, to avoid drug-resistant pathogens.

Can PRO F be mixed with disinfectants or organic acids?

No. The PRO F label says not to mix it with antibacterial agents or organic acids. Use an opened pack within 30 days.

At what size are fingerlings sold?

This protocol runs to a harvest size of about 30 fish/kg (about 33 g each). Fingerlings must be free of bacillary necrosis before leaving the pond or moving to grow-out ponds.

References

Protocol compiled by the Than Vuong Technical Department for reference. Ponds differ in water source, stocking density and weather; contact our technicians to adjust it to your pond.