Introduction to Pangasius fish farming
Pangasius is also called a river or silver striped catfish, Siamese shark, and swai catfish. Pangasius is a riverine catfish belonging to the members of the family Pangasidae and it exhibits fast growth when cultured given a good environment.
Pangasius fish has a long body, latterly flattened with no scales, relatively small head, broad mouth with small sharp teeth on the jaw, and relatively large eyes. Young fishes have black stripes along the lateral line while large adults are uniformly grey but sometimes with a greenish tint are found. Pangasius is a highly migratory riverine fish species. Pangasius is cultured due to its strong market demand; few countries dominate the cultural production, and also being the 3rd most important freshwater fish group within the aquaculture sector. It is now cultured in several countries in the world like Thailand, Nepal, Pakistan, India, Bangladesh, Vietnam, Laos, Myanmar, Indonesia, and Cambodia.
A step by step guide to Pangasius fish farming
In India, Pangasius fish can be farmed under monoculture or polyculture with carp species. The species can grow to 1 to 1.5 kg in one year, and annual yields are 10 to 15 tons per hectare. It is found in freshwater, it can live in salt concentrations of about 0.7% to 1% and alum water (pH >5) which can be tolerated at temperature ranges of around 30°C. With a streamlined body, dark grey colored back, silver belly, wide mouth, and long twin beard, it has more red blood cells than other fish, an additional respiratory organ, and can breathe through bubbles and skin. Then, this means it can tolerate environments with little dissolved oxygen.
The Pangasius fish grows up quite rapidly and young fish grow mainly in length, and after two months in the breeding stage, baby fish can reach a length of 10 to 12cm and weigh 14-15gram. When they reach a weight of about 2.50 Kg, the rate of subsequent weight gain becomes quicker than their rate of growth lengthwise. Though, fish of 10-years-old or older grow only in weight. Pangasius fish weighing about 18 Kg and 1.80 meters in length have been found. In farming ponds, parent fish can reach a weight of about 25 Kg by the age of 10. As for commercially farmed fish, those weighing from 800 grams to 1,100 grams, after 6 to 8 months, excluding the breeding stage of 2 months, are best for harvesting.
Feed and nutrition in Pangasius fish farming
Feeds and the procurement and the usage of raw materials for feeding are vital to the success and sustainability of Pangasius aquaculture. But aquaculture in general can be viewed in a negative light when it comes to the issue of feed due to concerns for and perceptions of sustainability and the use of physical resources and biological resources. The use of feed, feed practices, and potential advances in feed manufacturing can have a significant impact on sustainability.
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Nutritional requirements of Pangasius
The Pangasius as a nutritionally low input species and this means that it can be produced efficiently with little animal protein, fishmeal, and fish oil. Pangasius is produced using feeds of 28 to 32% protein that primarily consist of grain-based materials or derivatives. It can be produced using homemade feeds or agricultural by-products as well as additional nutrition from natural pond productivity (Pangasius can consume sediments and detritus to gain nutrition from bacteria and organisms).
The low input diet of Pangasius is an advantage in terms of reduced feed costs and results in lower production costs and a more environmentally friendly product. Feed accounts for 70 to 90% of total production cost so for farmers, selecting a suitable product is of primary concern.
FCR (Food Conversion Ratio) and feeding practices of Pangasius
The feed conversion ratio (FCR) of Pangasius that are fed commercial pellets is around 1.7-19:1. Pangasius feeding is mainly divided into two stages. The first tends to use feed with high amounts of protein in Pangasius fish and minerals than the fish gain maximum length. In the second stage, the carbohydrate concentration of homemade feed is increased to fatten the fish, make them heavier, and thus result in higher production. Improvements in feed can contribute to increases in growth rate, fish survival, and a shortening of the culture cycle.
Nursery management in Pangasius fish farming
Nursing is done in two separate stages to reduce stocking density. Earthen nursery ponds, normally 1000-5000 m2, are pre-prepared by drying (1-3 days, depending on the season), liming (1 t/ha), filling, and stocking with Moina. Though, water supplied to nursery ponds is filtered through fine-meshed cloth to exclude predators. In the first nursing phase larvae are stocked at 400 to 500/m2 just before yolk sac absorption, so that natural feeds are available and the larvae have enough space to avoid cannibalism. Water is topped up and is not exchanged during the nursery phase unless water quality deterioration is causing stress. Boiled egg yolk and soybean meal mixed into an emulsion are fed 5 to 6 times a day for the first 2 weeks. Thereafter commercial pellets are fed.
After 4 weeks, following a 24 hour starvation period the nursery ponds are partially (about 1/3 depth) gravity drained and then pumped dry, and the 0.3 to 1 g fry are harvested by seine net and transferred and stocked at 150 to 200/m2 in another pre-prepared pond without Moina. Typical larvae to fry survival rate during the first nursing stage is 40 to 50 percent. In the second nursing stage, from fry to 14 to 20 g fingerlings, survival rates over the 2 month nursing period are typically 60-70 percent.
The majority of fingerlings are transported from nursery to grow-out farms in transport tanks with continuously pumped water that is carried in boats. Fingerling transport is done early in the morning to avoid direct sunlight and transportation of fingerlings overland is less commonly conducted; this involves using metal drums with car battery powered aeration. Additionally, transportation overland for short distances can be carried out in metal drums without aeration.
Construction of pond for Pangasius fish farming
Earthen ponds (normally ranging from 1 000 to 10 000 m2) are of simple design and sited adjacent to or near river tributaries. Producers aerate the ponds and exchange water for several hours daily during the culture period by tidal exchange; this reduces muddy off-flavor and produces whiter flesh. Despite recommendations from government extension agencies to stock about 20-40 fish/m2, intensive monoculture ponds are usually stocked at 40 to 60/m2, with some grow-out farmers stocking even higher. Yields reach 250 to 300 tonnes/ha/crop, exceptionally reaching 500 tonnes/ha/crop in ponds. Striped catfish reach 1.0 to 1.5 kg after 6 months or less, depending on the size of fingerlings stocked.
Net cages are sited on major river tributaries and range in size from 50 to 1600 m3 with larger cages having living quarters above the water. On growing cages are typically stocked at 100-150/m3 and yields are 100-120 kg/m3/crop.
Stocking densities for pen systems are 40 to 60/m2, producing yields of 300-350 tonnes/ha/crop, although levels as high as 500 tonnes/ha/crop have been are reported.
Care and shelter requirement in Pangasius fish farming
Mainly the land which is not good for agriculture farming is used to make fish farm. For fish farms some points must be kept in mind such as the land should have water holding capacity, don’t make a pond on sandy and loamy soil. If you want to do soil testing then at that land dig about 1 foot wide and deep hole and fill it with water. If the water remains in the hole for 1 to 2 days then it is good for fish farming but if no water remains in the hole then it is not good for fish farming.
Culture of Pangasius fish
Primarily reared in ponds and cages, Pangasius fish is stocked at high densities (around 60 -80 fish per m2) and grown for around 6 to 8 months before reaching its harvest weight of around 1kg. Males and females grow at similar rates, with the reproduction temperature range between 26 and 28°C. The spawning period is between February and October, with the age of maturity known to be 3 – 3.5 years. Pangasius is highly fecund; females can produce up to 80,000 eggs/kg and can be spawned several times. Pond production can lead to yields of about 250 – 300mt/ha, more than 4 times that of other aquaculture species.
Cage production occurs in impoundments, lakes, or rivers, and stocking densities tend to be around 100 – 150 fish/m3 and yields from around 100 to 120kg/m3. Floating cages help maintain continuous water exchange and allow higher fish densities and productivity. Floating feeds and good water quality lead to white fillets, though yellow flesh is said to come from non-commercial or natural food sources. Today, farms are obliged to give information on any possible environmental impact before farming operations can begin.
Pangasius exhibits a range of potential advantages in terms of reproductive capacity, resistance to low dissolved oxygen, and also production yields. As the demand for safe and sustainable seafood continues to go up, the culture and consumption of Pangasius can likely become more mainstream.
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Feed management in Pangasius fish farming
Pangasius fish can be fed with kitchen waste, rice bran, or pelleted feeds (recommended for faster growth and better fish quality) at a rate of about 2.5% of their average body weight (ABW) and will be adjusted bi-weekly. Pangasius fish FCR averages to 1.5:1; this makes it suitable for culture. There are two types of feed available, that are floating and sinking feed. Different breeds of fishes prefer different feed for example shrimp will eat shrinking feed. The feed is obtainable in the form of pellets ranging in different sizes according to the size of the fishes.
Pangasius fish feed has developed greatly over the years. One example is an industrial feed that can reduce some diseases and environmental pollution by feed residuals, but the industrial feed is more expensive than homemade feed. Also, young fish cannot feed well on the homemade feed so the industrial feed is used during the first 2 months of the grow-out culture system. When the market price for Pangasius fish drops, farmers tend to apply both industrial and homemade feed.
Homemade feed – This consists of mainly two ingredients, rice bran and trash fish in different ratios to provide good protein content during periods of growth. Farmers have begun using alternative protein sources such as soybean meal, corn, dried fish, meat bone meal, and poultry. Farmer’s mix rice bran, trash fish, and other ingredients cook the mixture and use an extruder to create a sticky and long string feed. Feed additives are included as they enhance feed quality, fish health, and fish growth. Examples of feed additives are vitamin C, lysine, anti-oxidants, vitamins, and mineral premix. Homemade fresh feed is made from materials that are rice, fishmeal, and soybean. These are finely ground, mixed, cooked, and cooled before being made into small handfuls and pressed into pellets.
Commercial pelleted feed – This type of feed is dried and pelleted by industrial processing lines. And an increasing trend towards the use of commercial pellets that contain rice bran, maize, and fishmeal. Though they are more expensive, they result in better feed conversion ratios and water quality and are designed to float to avoid any build-up of food in cages or at the bottom of ponds. Some farms use commercial pellets throughout the on-growing procedure, and others only in the first and last month while the fish are given farm-made food.
Water management in Pangasius fish farming
Water is important for all fish, so optimum conditions for certain parameters of water must be the primary factor to consider in engaging to fish culture. Water quality parameters like pH level (6.5-7.5), Dissolve Oxygen (DO) (0.1 mg/l), Pangasius fish temperature (25-30° C), Salinity (<2 ppt) and water depth (1.5-2m). These must be maintained to get a better yield for the culture of Pangasius is an air-breathing fish thus; they don’t need to have a much higher Dissolved Oxygen in the water column.
The cost of Pangasius fish
The cost of Pangasius Fish is approximately Rs 90/ Kg (retail), however, you get less price at the farm gate.
Diseases and treatment of Pangasius fish
To increase production and maximize the profit, the farming of Pangasius has been intensifying, but with this comes a risk of increased disease caused by viruses, bacteria, fungi, parasites, and pathogens. One main constraint to Pangasius farming is a disease, which generates high costs in areas such as prevention and treatment.
As long as culture conditions are good, Pangasius is resistant to disease during the grow-out period but deteriorating water quality, handling, or low water temperatures can all increase the likelihood of parasitic or bacterial infections. Common diseases of pangasius are given below;
Tail and fin rot – The symptoms are rotting of tail and fin, light white color is seen at the corner of the fin, and spread all around the fin and then finally fall.
Treatment – Treatment with copper sulfate at 0.5% is done. The fish is drowned in treated water for 2 to 3 minutes.
Gill rot – The symptoms are gray color gills and they finally fall. Then, the breath of fish will squeeze and they come at the upper layer of water to take the breath and at the end, they will die due to breath squeezing.
Treatment – Fishes are drowned in 3 to 5% saltwater for 5-10 min to treat from the disease.
White spot disease – White patches are seen on skin, gills, and fins of the Pangasius fish.
Treatment – Drown the fish into formalin solution at 0.02% for 7-10 days for 1 hour.
Black spot disease – Small spots of black color are seen on the fish body.
Treatment – Drown the fish into a picric acid solution at 0.003% for 1 hour.
Argulosis – The main symptoms are slow growth, loose fin, and blood spots on the skin.
Treatment – Add Malathion (50 EC) at 1l/acre at the interval of 15 days for 3 times.
Vibriosis – The symptoms are white or grey color lesions are found on the spleen and intestines.
Treatment – Dose of oxytetracycline at 3 to 5gm/100lb of fish/day is given for 10 days or the dose of Furazolidone is given in feed at 100mg/kg/fish for 6 days.
Red mouth disease – The main symptoms are reddening of fins, mouth, throat, and gill tips.
Treatment – Several antibiotics and vaccinations are available which are used to cure red mouth disease.
Harvesting stage of Pangasius fish
The harvesting stage can be done in partial (selective harvesting) or total harvesting. Pangasius can be harvested for about 5 to 6 months of the culture period. It can reach the weight of 1-1.5 kilograms in 5 to 6 months culture given the proper pond management. It can be harvested after 5 to 6 months of culture period when its weight reaches approximately 1-1.5kg.
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