High-yield polyculture fish farming techniques
1. Prepare the pond
- Drain and dredge mud, leaving only a layer of mud 15 - 20cm thick.
- Clear the bushes to create an open surface for the pond.
- Secure embankment, check and fill leaks
- Sprinkle lime powder at a dosage of 7-10kg for 100m2 of pond area.
- Fertilization: after 3 days of de-liming, apply basal fertilizer by spreading evenly over the pond 20 - 30 kg of composted manure and 50 kg of green leaves for 100 square meters (leaves of soft-stemmed plants to make green manure). Green leaves are chopped and spread evenly over the bottom of the pond, buried in mud or tied into small bundles of 5 to 7 kg and buried in the corner of the pond.
- Fill the pond with water from 0.3 - 0.4 meters, soak for 5 to 7 days, remove all the green manure residue, fill the pond with water to a depth of 1.5 - 2 meters. Note: it is necessary to filter the water into the pond with a filter net with small mesh size to prevent predatory fish and miscellaneous fish from entering.
2. Release the seeds
- Fish density is 1-1.5 fish/m2, in places with clean water source and convenient access, you can raise 2-3 fish/m2
- Fish are released when the weather is cool, such as early morning or late afternoon.
- Before releasing the fish, the fish need to be balanced with the pond water environment by immersing the fish bag in the pond for 10-15 minutes, then slowly opening the bag to avoid shocking the fish to the environment.
Illustration photo
3. Co-culture ratio
The polyculture ratio depends on pond conditions and food supply.
Some formulas for fish breeding.
* Mainly raising tilapia
Tilapia 60 - 70%
Grass carp 10-15%
Other types 20-25%
* Mainly raising grass carp:
Grass carp 50%
Grass carp 25%
Grass carp 20%
Carp 5%
* Mainly raising grass carp
Grass carp 50%
Grass carp 20%
Grass carp 10%
Carp 10%
Mrigan fish 10%
Currently, most farmers mainly choose to raise monosex tilapia, carp, and grass carp.
4. Care
Regularly check the fish pond every morning and afternoon for unusual fish activity.
The 4 principles of feeding: quantity, quality, time and place.
Food portions:
Fish size up to 100g 3 – 5% of fish weight
Fish size <100 – 300 g 2 – 3% of weight
Fish size > 300 g 1.5% of fish weight.
- Feed the fish twice a day: 6-8am in the morning and 4-6pm in the afternoon. Reduce the amount of food on days when the weather changes. Do not feed the fish when they show signs of floating.
5. Disease prevention measures for fish
5.1. Comprehensive disease prevention
+ Periodically use 1 - 2 kg lime/100 m3 of water/week. When it rains, use 2 kg lime/100 m3.
+ Hang 2-4kg lime bags/bag at feeding points
+ Before releasing, bathe the seeds in salt water 2-3kg/100 liters of water for 5-10 minutes.
+ Choose the appropriate formula and farming object for each pond.
+ Periodically use biological products such as EMC, BIODW, BIOBAC… to improve the pond water environment.
+ Add 200 - 300g of vitamin C per 100kg of food, feed fish regularly to increase fish resistance.
+ Changing water for the pond: in places with favorable water sources, we can regularly change and add new water to the pond. The amount of water changed is from 20 - 30% of the water in the pond.
5.2. Disease prevention with some herbs to prevent fish diseases:
+ Banana tree: cut the trunk into small pieces and cut the leaves into pieces to feed the fish.
+ Garlic: Crush garlic and mix it into food at a dose of 0.5 - 1kg/100kg of food. Feed for 6 consecutive days.
+ Purslane: wash with salt water and feed 1.5 - 3kg of vegetables/100kg of fish
+ Eclipta prostrata: grind to get the juice and use the residue to feed the fish with a dosage of 2-3kg/100kg of fish/day.
The above herbs are all good for preventing and treating intestinal diseases in fish.
6. Measures to treat fish diseases
6.1. Red spot disease in fish
* Pathological signs
- Fish eat less or stop eating, swim lethargically on the surface. Fish skin is dark, dry and slimy.
- Red spots appear on the body, the base of the fins around the mouth. Scales fall off and flake off, ulcers eat deep into the body with a characteristic fishy smell. The anus is red and swollen, the belly may be distended, the fins are torn, and the fin rays are gradually shortened.
- Anatomy: the abdominal cavity is hemorrhagic with a lot of fluid, internal organs such as the liver, spleen, and kidneys are hemorrhagic, the intestines have no food and may be full of gas, the hemorrhagic intestinal wall has many areas of necrosis and decay.
- Hemorrhagic disease occurs mainly in grass carp, bighead carp, and bighead carp...
- Disease outbreak season: spring, early summer and autumn.
* Disease prevention and treatment measures
- Treat pond water environment with one of the following chemicals:
+ 1 kg potassium permanganate for 1000m3 of pond water.
+ Vicato 1kg for 2,500 - 3,000m3 of pond water.
+ BKC 1 liter for 3,000 m3 of pond water.
- Disease prevention: use Chinese Tien Dac 1: 1kg medicine/2,000kg fish, feed for 5 consecutive days and feed once every 30-40 days. Disease treatment: use 1kg medicine/1,000kg fish, feed for 5-7 consecutive days combined with lime, add water, and increase concentrated feed.
- Mix KN04-12 medicine for fish with a dosage of 200g for 100kg of fish/day, feed for 5-7 consecutive days.
6.2.Gill rot in fish
* Pathological signs
- Fish swim separately, slowly on the water surface, catch less or no prey.
- The fish skin gradually turns black, the gills are torn, rotten and covered with mud. The surface of the gill cover bone is hemorrhagic, corroded and has an abnormal shape. The gill filaments are rotten, covered with mud, the epidermis inside the gill leaves is hemorrhagic.
* Distribution and spread of disease
- The disease often occurs in many fish species: grass carp, black carp, common carp, bighead carp.
- The disease appears in spring, early summer, autumn, suitable at water temperature 25 - 350C.
- The disease often occurs in fish raised in high density cages, poor water circulation, in fish raised in ponds with a lot of organic debris, fishermen call it "muddy gill disease".
* Treatment
- To treat the disease, you can combine antibiotics mixed into fish food for 5-7 days to kill pathogens inside and sprinkle lime powder into the pond at a rate of 1-2 kg per 100m3pond water to kill pathogens from the environment.
- Use antibiotic Erythromycin 4 g/100 kg fish/day.
- Use antibiotic Oxytetracycline 20 - 40 mg/kg fish/day.
6.3. Anchor worm disease.
* Pathological signs
- Infected fish have poor appetite, are weak, and have inflammation and bleeding around the anchor worm attachments. The anchor worm attachments create conditions for bacteria to invade and develop.
- The places where anchor worms attach themselves, to the naked eye, can be seen to resemble an anchor.
* Distribution and spread of disease
- The disease causes great harm to juvenile fish and fingerlings.
- Large fish and anchor worms do not cause major harm but create favorable conditions for other agents to invade such as fungi and bacteria, which will cause mass deaths.
* Treatment
- Use bundles of neem leaves and put them in the pond at a dosage of 5 - 7 kg/100m2.
6.4. Wheelworm disease
* Pathological signs
- The body and gills of the fish have a lot of opaque white mucus.
- The fish skin is gray, the fish are itchy, and schools of fish float to the surface of the water.
- When the disease is severe, the gill filaments are destroyed, the gills are filled with silvery white mucus. The fish swims around, then flips over and sinks to the bottom and dies.
* Distribution and spread of disease
- Usually external parasites such as gills and skin.
- The disease is common in some fish species: grass carp, common carp, silver carp, bighead carp, catfish... The disease mainly causes harm in the fry and fingerling stages.
- The disease appears all year round but mainly in spring, early summer and autumn. The suitable temperature for the disease to develop is 20 - 300C.
* Treatment
- Use 2 - 3% salt water to bathe fish.
- Use CuSO4 (green alum) 500 - 700 g/1000m3water.
7. Harvest
- Stop feeding the fish 2 days before harvesting. Raising fish in a high density with good investment in feed can yield 12 - 15 tons/ha/crop.
According to khuyennonghanoi - LY
