Eel is a very energetic fish and highly adaptable to different types of environments and farming conditions. However, to obtain high yield and delicious meat quality, farmers need to do it right eel farming techniques Follow the best guidance from experts. Please refer to the following article to master the technique of raising this high export value commercial fish of our country.
Preparing the pond
The best pond area is 500 – 1,000 m2, the pond must be built by mechanization. The water level must ensure an average depth of 1.8 – 2.2 m. The pond edge should be at least 60 cm above the highest water level in the pond. The pond bank is wide and solid, no water leakage. The quality of soil for building ponds is sandy loam, clay soil is the best. It is recommended to build 02 or more ponds to easily size the fish and change the water during the farming process. Around the pond system must be fenced with cement tole or solid nets to prevent fish loss.
Renovating ponds and treating water sources
For old ponds that need to be drained, slugs dredge all the bottom mud, apply lime CaO from 70-100 kg/1,000 m2 depending on the pH of the soil and dry to dry. For newly dug ponds, the amount of lime can be applied more and it is soaked to remove alum many times, then keep the water level 20 cm and then use a wire to grind fish from 2-3 kg/1,000 m2 to kill all trash fish.
It is necessary to induce algae to stabilize water quality and ensure oxygen content in the pond. Algae growth reduces transparency, prevents light from penetrating to the bottom of the pond, creating an environment suitable for the dark-loving behavior of eels. Splash water with DAP or NPK fertilizer with a dosage of 1-2 kg/1,000m3, so it is recommended to spray continuously for 2-3 days for algae to grow for green water.
Select varieties and stocking density
Because the source of eel seed is mainly caught from the wild, some places use fishing nets to catch seed, so farmers still have many difficulties in choosing breeds. Therefore, people should choose to buy seed at hatcheries from the juvenile stage, the fish have been nursed through many stages to help the quality of the fingerlings ensure the requirements when the fingerlings are pressed, rearing suitable for artificial rearing conditions. The most obvious manifestation is the fearless fish, swimming naturally on the surface of the water to find prey. Quickly catch prey when feeding.
When transferring fish, they should not be rushed into the pond, but should be placed in a tarpaulin tank with a water level of 0.8 – 1.0 m, the canvas tank is placed in a cool location combined with aeration and creating a flow for the fish to like. with water sources. Bath time is from 10 to 30 minutes or until the fish shows signs of discomfort.
Fish bathing is a very important step to remove bacteria, fungi as well as parasites for fingerlings, and through that, it will classify healthy fish for stocking first and weak fish, fish suspected of hooking will be fished. be kept in intensive care or released in separate isolation.
Stocking density depends on seed size and culture conditions. Here are some reference drop densities:
+ For semi-intensive culture (using fresh fish food without oxygen system), fish size should be 50-100g/fish: average stocking density is from 5 fish/10m2 to 1 fish/m2
+ For intensive farming (using industrial feed and with oxygen generation system), fish should be stocked from 25 to 100 g/fish: stocking density ranges from 4 to 10 fish/m2.
Care and management
Can use 2 types of food, fresh and industrial. Feeding according to the principle of 4 determinations: qualitative, quantitative, timing, and location.
The food has enough protein. If using trash fish food must be fresh, it is best to use tilapia, or sea fish. The fish is preliminarily cleaned, then cut to fit the size of the fish’s mouth at each stage to be fed. Industrial eel feed in powder form is produced from China, Taiwan with high protein content from 45 – 50%, very good quality but quite expensive.
Fresh fish feed every day for 5 – 15% of the total weight of fish in the pond; Industrial feed feeds 3 – 4% of the total weight of fish in the pond. Ask the food to drop down after 20-30 minutes, the fish must eat it all.
Feed 1 time a day at 8-9 am in weak sunshine or 4-5 pm. Industrial food before feeding fish needs 5-10 minutes to mix well with water at the rate of 1kg of feed + 1.5 liters of water, then mixed by machine and fed to fish right on a floating tray.
The position of the feeding sieve must be fixed. The feeding sieve is a square or circular frame with a size of 1m2 stretched with nylon mesh, the mesh size is large and small depending on the size of the fish. Place the food sieve in a dark, airtight place. For trash fish food, it is advisable to place the feeding sieve close to the bottom of the pond; and ready to eat using industrial feed floating on the surface of the water.
Prevention and treatment of diseases
5.1 Mycosis fungoides
- Eel is a new species, with few diseases. Fish often stop eating due to environmental factors and poor quality seed selection, leading to fish not eating and losing much. Eels also often encounter some diseases like other freshwater fish, but have not seen any harm to the fish. The main and most dangerous is fungal disease on eels, which is the cause of the greatest damage, sometimes up to 70-75%. Due to two varieties of fungi, Saprolegnia and Achlya. Harm: Eels are catfish, in addition to respiring by gills, eels also breathe mainly by skin. The fungus will interfere with the fish’s skin respiration leading to weak and dead fish.
- Disease prevention and treatment: Use potassium dichromate K2Cr2O7 at a dose of 20-25g/m3 directly into the pond to kill fungal diseases.
5.2 Fin rot disease
- The causative agent of the disease is the bacterium Flexibacte columnaris. This bacteria thrives at low temperatures, below 15 degrees Celsius. Symptoms are on the fish appear many white spots on the head and fins. The fin rays are necrotic and torn, the fish will also be poisoned by the toxins secreted by the bacteria and cause damage to the circulatory system. Severely ill fish will die within 2 days.
- Treat with Doxery 10 – 15gr/kg feed, or Vime – Glucan 5 – 10 gr/kg feed mixed with Glusome 2gr/1kg feed to strengthen the immune system and the resistance of fish.
5.3 Fish lice live on skin, fins, oral cavity and gills
- The disease occurs all year round, but usually concentrates in the rainy season. When the fish is young, it only takes 1-2 parasitic lice to kill the fish. Eels have a habit of living in hiding, so they are easy to be attacked by fish lice.
- Prevention and treatment of lice by cleaning the environment before raising fish with lime powder. When lice are found on fish, it is necessary to treat fish with potassium permanganate 2 kg/1,000 m3, need to check the pH of the water, create an alkaline environment by pumping underground well water or changing the increase or decrease in salinity will limit fish lice.
We hope that the technique of raising eels that we share will help you to have more skills for yourself. Wish you success in raising eels and get high yields.