Precautions for breeding giant salamander seedlings

Dazhu belongs to amphibia, cauda, Cryptobranchidae, commonly known as baby fish, is a specialty of our country, so it is also known as the Chinese giant salamander. Giant salamander is distributed in 18 provinces and cities in China, mainly in deep mountains and dense forests and streams in South China and Southwest China. Common weight 2~5kg, body length about 50~150cm, the largest individual can reach 10~20kg. Because of its delicate meat, delicious taste, rich nutrition and high edible and medicinal value, giant salamander has always been a popular healthy high-end nutritious food. In recent years, due to man-made excessive fishing and killing, coupled with the serious damage to the natural ecological environment, the resources of giant salamander are decreasing day by day, and they are endangered animals, so they are listed as the second category of key protected wild animals by the state. With the in-depth study of ecology and reproduction of giant salamander, artificial reproduction has been broken through, and the bottleneck of seedling supply and demand has been solved. Giant salamander artificial breeding farms have sprung up like bamboo shoots after a spring rain. For example, Wangcheng District of Changsha is not the origin of giant salamander, according to statistics, there are more than 100 giant salamander farmers in this area, raising more than 50,000 giant salamander every year. In a short period of 7 to 8 years, an aquaculture industry with an output value of more than 100 million has been formed. Due to rapid development, uneven breeding level, one-sided pursuit of interests, high-density intensive breeding, artificial over-feeding, rapid growth promotion, drug abuse, artificial control of the ecological environment, etc., lead to giant salamander culture diseases such as swollen head and foot disease, enteritis, skin rot and so on, some farmers due to weak technical strength, once the disease leads to complete destruction. Especially in the seedling culture stage, breeding management, disease prevention and other measures are not in place, resulting in a large number of deaths and serious economic losses to farmers. How to do a good job in seedling culture has become the key to giant salamander culture. The author visited a number of farmers and summed up the experience of success and failure. The author thinks that we should pay attention to the following key points in seedling culture of giant salamander.

Licensed culture

According to Article 17 of the Wildlife Protection Law of the people's Republic of China (adopted at the fourth meeting of the standing Committee of the Seventh National people's Congress on November 8, 1988): "those who domesticate and breed wildlife under special state protection shall hold a license." Giant salamander is a national second-class protected aquatic animals, so the new farmers must first apply to the relevant departments to obtain a breeding license before breeding giant salamander. The specific method is that the farmers apply to the fishery administrative department of the county or city (administrative department) government, after examination, submit to the fishery administrative department of the provincial government for approval, and obtain a license before breeding, otherwise it will be regarded as illegal.

Construction of seedling pond

The seedling pond of giant salamander is generally a pool with cement structure, with an area of 1: 2 and a depth of 20~30cm. As the skin of giant salamander in the seedling stage is relatively delicate, ceramic tiles are required to be affixed to the bottom and wall of the pond to reduce the friction between giant salamander and rough surface, and the aquaculture pond is thoroughly disinfected one week before use. The newly repaired culture pond has strong alkalinity, and the strong alkali has a strong stimulation to the giant salamander, causing skin and body damage, so the newly repaired culture pond should be soaked in water for two months, and the water should be changed for 2 or 3 times; if the time is short, the seedlings can be soaked with oxalic acid for about 10 days, and then soaked in clear water for 2 times, and the seedlings can be put in a month later.

Seedling selection, purchase and transportation

The best way to purchase the seedlings of giant salamander is to choose and purchase the seedlings naturally propagated in the breeding farm nearby, and the breeding farm is required to have the license for aquatic wild management and utilization of giant salamander, and at the same time do a good job in quarantine. Also pay attention to the following items when choosing and purchasing:

1. First check the health status of seedlings or species of salamander, requiring no disease, no injury, and normal activity rules. Artificial reproduction and natural reproduction of fish fry preferred natural reproduction, because of its good disease resistance, strong immunity. Stop eating for 2 days before buying, so that the fish will not spit and burst their belly, especially the saplings. If you want to buy fish fry with gills, not only oxygen should be filled in the oxygen bag, but also bottled ice and other methods should be taken to cool down in the packing box when the temperature is high.

2. The best transportation plan should be made before transportation, such as the choice of traffic route and transportation time. Choose the nearest and avoid the rush hour, and complete the transportation task in the shortest possible time.

3. The young salamander transported back should not rush to open the bag and enter the pool. The fish and the transport bag should be put into the pool to soak for a while, and then open the bag when the temperature in the bag is the same as the temperature in the pool. Before entering the pond, the young fish can be soaked in a certain concentration of potassium permanganate solution for a few seconds, sterilized and sterilized before entering the pond. Don't rush to feed in the first 2 days, let it starve for 2 days, adapt to the environment and then feed.

Seedling rearing

The young salamander which has just taken off the membrane is about 2.0cm, lying on its side in the water, with very little exercise and weak swimming ability, relying on its tail to swing in the water, usually swimming once in 1-2 hours. The newly hatched young salamander, after about 30 days, the yolk has been exhausted, at this time the young salamander began to eat. Timely feeding time is very important, feeding too early, young salamander has not opened, do not have feeding ability, bait organisms in the water not only to consume a lot of oxygen in the water, affecting the growth of young salamander, but also produce pollution; feeding too late, young salamander yolk energy depletion predation ability decreased, unable to catch bait, or closed mouth did not eat, and finally died. At present, the commonly used opening bait of young salamander is artificially cultivated red worms. Opening bait requirements: first, the individual size is palatable; second, the activity ability is weak, swimming speed is slower than young salamander, easy for young salamander to ingest; third, clean, no mud, no dirt; fourth, it is best to live; fifth, the amount of bait should be sufficient.

In the early stage, due to the poor activity ability of young salamanders, in order to facilitate the management and cleaning of breeding ponds, they are generally raised in plastic baskets, not more than 5 per square centimeter, and should be sparse in time with the growth of giant salamanders, and can be raised in cement ponds directly to 6~7cm. In the process of feeding, water is required to filter to ensure fresh water quality, no pollution, and the water should not be too deep, so as to cover the fish and the fish can swim freely. Keep micro-running water in the pond and clean the fish pond every day.

Feeding quantity

The nature of bulimia is gluttonous, and its living habit in nature is to go out at night. It is better to feed it in the evening, and it is appropriate to feed the young salamander until it is 780% full. In the young salamander period, sometimes a small amount due to excessive food intake, to the abdominal swelling is too big to swim, floating on the surface can not be sunk in the water, these young salamanders should be placed separately in the plastic basket, placed in the shallow water area, let them lie flat to reduce their activities as far as possible, after 2 days, wait for the abdominal swelling, and then put into the pool.

Diet conversion

After about 5 months of feeding, the seedlings can reach 10~12cm in length. At this time, they should change their feeding habits and feed on small fish and shrimps. The specific approach is: choose fresh fish, remove fish bones, chop into surimi and feed with red worms. At the beginning, a small amount of surimi was mixed, and the amount of red worms was reduced correspondingly. After 3 days, the amount of surimi was gradually increased and the amount of red worms was reduced, and finally all the surimi were fed. After 15 days and 20 days, all the seedlings could be converted to eat fish, and the young salamanders who changed their eating habits could be fed with palatable live fish and shrimp.

Disinfection management

Disinfection management is very important in giant salamander seedling culture. To do a good job in this work, we should do the following:

1, breeding ponds and tools disinfection: seedling breeding tools, to achieve a special pool, after each use should be soaked with salt or potassium permanganate. At the same time, the culture ponds and seedlings were soaked in povidone iodine and other fish disinfectant for 0.5 hours every 10 days.

2, bait disinfection, feed should be fresh, whether red worms or fish should be soaked in 5% salt water before feeding, rinse with clean water and then feed.

3. In daily breeding, we should pay special attention not to touch the young salamander as far as possible, such as to divide the pond and other operations to use small copying net. For mechanical injuries, bite injuries, diseased young salamanders should be isolated and treated in time.

4. at the same time, avoid reducing series between farms as much as possible, such as touching diseased fish from other farms, hands and other items should be strictly disinfected. It is best not to enter your own breeding area on that day to prevent diseases from spreading to each other.