Nowadays, there are many different effective ways to raise eels. Thanks to the stable economic returns earned from selling eels, many people have taken the time to learn about raising eels in cement tanks. This method is quite new and has only recently appeared in our country. So, what are the advantages and disadvantages of this eel-farming method? Let’s follow Đức Bình Microbial Products as we look at the article: How to raise eels in a cement tank the right way below
The most effective way to raise eels in a cement tank
1. How to Correctly Raise Eels in a Mudless Cement Tank
The model of raising eels in a cement tank has only appeared recently, but because it delivers such high effectiveness, it is increasingly being applied widely. The first thing to do is to build a cement tank of a suitable size, using the right materials. Typically, a cement tank suitable for raising eels should have a depth of 0.8 to 1m. At the same time, the total area must be from 5 to under 10m2, with wall thickness of 12 to 15 cm.
In addition, the inside of the tank must be finished with well-cured cement to create a certain smoothness and glossiness, so as not to injure the eels’ skin surface. You can also line the inside with ceramic tiles instead of cement. This option also ensures aesthetics and cleanliness, allowing the eels to move around easily without scratching their skin. Next, the inside of the tank also needs a place for the eels to take shelter, since their natural habit is to live under tree hollows or burrow into holes.
Model of raising eels in a cement tank
Building shelter racks inside the cement tank
Building shelter racks for eels not only helps them quickly adapt to the environment inside the tank but also helps them grow faster. Some eel farmers share that once good growing conditions are ensured, the eels grow quickly and the harvest time is shortened, the eels are also less prone to minor illnesses, do not refuse food, and produce a batch that is uniform in size, without deformities. This shows just how important it is to equip the cement eel tank with shelter racks.
To build a shelter rack, we need large bamboo or wood cut into small strips. Make the rack from these materials by nailing the bamboo or wood strips together with a gap of about 10 cm. Households should make the rack about ⅓ the size of the tank and build 3 shelter racks. Once done, stack the 3 shelter racks on top of one another, adding a layer of netting on top to feed the eels. Also, one small note is that the shelter rack must be fixed in the middle of the tank, and the water level must be maintained at 25 to 30 cm.
Building a shelter rack for eels
Choosing good eel breeding stock
After finishing a cement tank built to proper standards for raising eels, farmers need to learn about and choose good eel breeding stock. There are currently two basic sources of eels you can buy: wild-caught eels and farm-raised eels. Each type of eel stock has a different price as well as different characteristics and quality. Wild-caught eels, when brought in for farming, are usually healthier, less prone to minor illness, and grow faster. However, nowadays farm-raised eel stock is also of comparable quality. Farmers can choose depending on their purpose.
For the eels to grow well in a cement tank, before putting the eels into the tank, farmers should bathe the eels in 3% pure saltwater. This ensures the eels stay healthy and can easily adapt to their new living environment. When placed into the tank, the eels must be stocked at a density of 40 to 60 eels per square meter for small eels, or newborn eels around 10 days old. For eels that are already 2 months old, reduce the density to 25 to 35 eels per square meter.
Choosing good eel breeding stock
How to care for eels raised in a cement tank
The main food for eels is trash fish, clams, snails, and snail worms. To make it easy for the eels to eat and digest, farmers should grind the food finely or steam it thoroughly, then mix in vitamin C or digestive enzymes at a dosage of 4g to 5g of enzyme per 1kg of food. This helps the eels eat well, absorb nutrients effectively, and stay healthy.
During the first 10 days of raising, you should only feed the eels once a day, in the evening. After that, we gradually train them to eat earlier. Once the eels are eating more, farmers should increase feeding to 2 times a day. Note that the daily amount of food is equivalent to 5% to 7% of the total weight of the eel population.
For small eels of about 1,500 per kg, farmers should raise them at a density of 1,000 to 1,500 per m2. The food for small eels is finely ground trash fish mixed with 20% pellet feed containing over 35% protein.
After about 3 months, once the eels reach a weight of 50 to 70 per kg, farmers can raise them at a higher density. The food for them at this stage is cooked trash fish equivalent to 3 to 5% of the eels’ body weight. Note that they should be fed once a day between 6pm and 7pm. The water in the tank must be changed once a day.
After about 6 to 7 months, once the eels reach a weight of 0.2kg to 0.3kg each, they can be sold on the market. According to long-time eel farmers who raise eels in cement tanks: during the raising process, every 30 days farmers should sort and separate the smaller eels from the batch to raise them separately. This way, the eel sizes will be more uniform, reducing the situation where larger eels eat the smaller ones.
How to prevent disease in eels raised in a cement tank
In fact, eels are very sensitive to the water environment in the tank. Many eels get sick due to water pollution or bacterial contamination in the water. Therefore, when raising eels in a cement tank, farmers need to have a disease prevention plan for them:
- The tank must be built to proper technical standards and thoroughly cleaned before releasing the eels into it
- Before being released into the tank, eels should be bathed in 3% saltwater for 15 to 20 minutes for disease prevention purposes.
- During the first 2 months from when the eels are released, we must completely change 100% of the water in the tank periodically every 1 to 2 days.
- From the 3rd month onward, the water-changing schedule can be less frequent, but attention must still be paid to cleaning up leftover food, waste, and sediment in the tank.
- The water in the tank must be clean, disinfected, and have enough oxygen for the eels to develop healthily.
- Regularly monitor the eels; if any show signs of illness or abrasions, separate them from the batch, carefully investigate the cause, and treat them promptly.
- Use microbial products specifically designed for freshwater aquaculture, sprinkled into the tank to prevent disease in the eels. Farmers should follow the dosage instructions from the manufacturer.
- Ensure the ambient temperature of the farming environment stays between 23°C and 27°C.
Using microbial products when raising eels
To raise eels effectively in a cement tank, farmers need to know how to clean the tank properly to maintain a stable living environment for the eels. This helps prevent quite a lot of risks, such as eels getting sick, eels dying and decomposing right in the tank, affecting the rest of the population. Therefore, choosing suitable cleaning methods is extremely necessary. Nowadays, the simplest, fastest, and most effective way to clean the tank is to use microbial products.
Microbial products are products refined from active ingredients that are harmless to livestock but effective at killing bacteria and cleaning the living environment. There are many different types of biological products suited to each type of farming. For raising eels in a cement tank, you can choose either powdered or liquid microbial products. These products help remove foul odors, fishy smells, and harmful bacteria, helping to protect the health of the livestock.
Powdered microbial products
First, the most popular type of microbial product chosen by many eel farmers is the powdered form. Its outstanding benefits include breaking down leftover food and removing foul odors from the tank without affecting the natural pH level. At the same time, the product dissolves easily in water, helps filter the water clean, and delivers fast results. The product is made from beneficial enzymes commonly used in production and farming, so users can be completely at ease.
Emzeo TS product has many uses in aquaculture – a powdered microbial probiotic that keeps eels healthy, growing fast, and less prone to disease
Liquid microbial products ( EM Stock Solution for Aquaculture)
Another type of microbial product used by many farmers is the secondary liquid product. This type has similar uses to the powdered product but dissolves in water faster and more effectively.
Depending on the volume of the water tank, you should consider the appropriate amount of microbial product to use. Typically, households raising aquatic species such as fish, shrimp, and crab also use this type of product. It dissolves easily and also helps remove harmful bacteria in the water, effectively balancing the pH level.
Using liquid microbial products to raise eels brings surprising results
2. Timing and Methods for Harvesting Eels
Eels are considered to meet the standard when the entire batch has a similar length, size, color, and weight. Large, healthy, quality eels will be sold at a higher price compared to small or deformed eels. Therefore, to ensure the eel batch you raise achieves the highest effectiveness, you need to know the right time to harvest. This not only helps save time and costs on food, microbial products, and so on, but still delivers a batch of eels that meets the standard.
The best time to farm eels with good breeding stock is around September to October. This is when eels breed abundantly, providing a high-quality source of eel stock. Farmers can buy eel stock during this month and raise them for about 3 months before harvesting.
Note that before harvesting, do not feed the eels for 24 hours. Also, use a basket to gently scoop up the eels, avoiding scratches to their skin surface. This harvesting method is simple but ensures the eels stay healthy and do not lose value when sold.
Harvesting eels
3. Common Diseases When Raising Eels in a Cement Tank
If you plan to raise eels in a cement tank, besides learning about the farming method and nutrition regime, you also need to know about the diseases that commonly appear in them:
Heat Fever Disease
The root cause of this disease is raising eels at too high a density, which reduces the oxygen level in the water and causes the eels to become sick. The signs are: the eels in the tank become agitated, curling tightly together into a clump, producing a lot of mucus, the water temperature rises noticeably, the eels’ heads become swollen, and they may die en masse.
How to treat heat fever disease in eels: as soon as signs of the disease appear, reduce the stocking density by transferring some eels to another tank, then change the water. To lower the temperature, we can add a 0.07% copper sulfate solution to the water. 24 hours later, change the water for the eels.
Ulcer Disease
Parasites are the main cause of this disease. Eels with abrasions are prone to this disease because the abraded area is exactly where parasites attach themselves in order to grow.
Signs of the disease: many ulcers appear on the eel’s body, and they may even lose their tails, have difficulty moving, and frequently raise their heads above the water surface.
How to treat ulcer disease in eels: properly disinfect the tank before releasing the eels into it. Breeding eels must be bathed in an appropriate concentration of saltwater before being released into the tank. During the peak season for this disease (May to September), farmers should also use an additional 2 to 3g of potassium permanganate per m3 of water, sprinkled evenly throughout the tank.
Nematode Disease
Eels raised in cement tanks also commonly face nematode disease. This disease is caused by intestinal parasites. When infected, eels show the following symptoms: swollen, red anus, slow and weak movement, and gradual death. In this case, farmers can use potassium permanganate at a concentration of 2 to 3g/m3 of water, sprinkled throughout the tank, or use Iodine at 1 to 1.5g/m3.
Above, Chephamvisinh.vn has shared some basic information about how to raise eels in a cement tank and the methods to help protect the health and best quality of the eels. We hope our article will be useful to you. Don’t forget to share this article with your family and friends!
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Đức Bình Microbial Products – Center for Research and Application of Biological Products, specializing in researching, manufacturing, and applying product lines such as: probiotics, septic tank enzymes, wastewater treatment enzymes, microbial products for aquaculture, biological products, and more…
Address: 1B Ngõ 774 Kim Giang, Thanh Liệt, Hà Nội
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