The southern bigmouth owl, also known as the bigmouth owl, is commonly known as the Dahe River, the 鲶Barolang, the fork 鲶, the 鲶é², and so on. The bigmouth turtle has strong adaptability and fast growth, and its meat is delicate, delicious, with less intermuscular puncture, and it is not greasy. It is not only a delicious meal on the table, but also has nourishing, yin, diuretic, breast milk, diabetes, and edema. And other medicinal effects. The whole fish is crushed into hot mud, which cures vitiligo, and can be used to cure hernia and acne. The consumer market is vast, and it is also favored by people in Europe, America, Hong Kong, Macao and Taiwan. Artificial breeding has high economic benefits and is a good breed that is generally welcomed by consumers and producers.
With the same species as the southern bigmouth owl, the river cricket (commonly known as the local cricket) is common. The river rafts are widely distributed. The rivers and lakes around the region are widely produced and grow faster. They are second only to the big tugs. The common one weighs about 500 grams and the largest individual reaches 20 kilograms. Some people now use it as a breeding object.
(A) source of varieties
The southern estuary is mainly distributed in rivers and rivers of the Yangtze River. Due to the excellent quality of the fish, the Sichuan Fisheries Research Institute first conducted artificial domestication and aquaculture research in 1985. In the domestication process, it can change its food habits, that is, from the original eat only live meat and shrimp and other meat into artificial feed can be eaten, can adapt to large-scale, intensive artificial breeding, and higher economic returns. Since 1992, the farming area has gradually expanded to the provinces, cities, and autonomous regions of Central and South China, East China and South China, and its production has increased significantly.
(b) Characteristics
The southern part of the mouth is large, flat and broad-necked, with a thick chest and abdomen, long tail and flat sides; the body surface is smooth without scales, and the skin is rich in mucus; the eyes are small and the mouth is large, hence the name; there are two nostrils on each side, and the front and rear nostrils are far apart. The frontal nostril is short tubular and is located at the snout end. The rear nostril is circular and is located at the front of the eye. Upper and lower jaws are distributed with inwardly bared fine teeth; adult fish must be 2 pairs, juvenile stages must be 3 pairs; caudal fins concave, upper and lower leaves asymmetric, upper leaves longer than the lower leaves; intestinal short, with stomach; back The body side is usually gray-brown or tan, and the abdomen is gray and white, with small black dots, and each fin is grayish black.
The bigmouth scorpion fish is lurking in the hiding place of low light during the day and dispersed in the water layer to scramble. Its docile nature, poor jump, will not mud. The water temperature for survival is 0-38°C, the suitable water temperature for growth is 12-31°C, and the optimal temperature is 25-28°C. For ferocious carnivorous fish, prey on various fish and shrimp and aquatic insects. The phenomenon of similar disability is serious and can even swallow the equivalent of 2/3 of its own body length. It grows faster, and the body weight of one-year-old fish can reach about 500 grams. Under the conditions of artificial rearing, the year-round fry can reach 600 to 1500 grams in weight, 2250 grams in the second year, and 4,000 grams in the third year. The largest individual up to 40 kg. In the area south of the Yangtze River basin, it can grow relatively quickly throughout the year, and is most prosperous in summer and autumn, with a daily gain of 3-5 grams.
In natural waters, mature hens with a body length of 80 centimeters are sexually mature at the age of 4 and can grow more than 40,000 eggs. Spawning period from March to June, spawning water temperature 18-26 °C, the optimum 20-23 °C. Its egg oil is yellow, transparent and flat-shaped, and it is sticky when it comes into contact with water. When the water temperature was 22 to 25°C, the fertilized eggs hatched for 40 hours. The newly hatched larvae have a large yolk sac, which can only swing at the tail when lying on the side of the water. After 2-3 days, they can swim freely and start to feed.
(III) Seed Breeding
1. Artificial propagation: High quality broodstock is the key to the success of artificial reproduction. Parents should weigh more than 10 kilograms. They can feed fresh feed during broodstock breeding, such as small trash fish, livestock and poultry, etc. They can also be fed artificial compound feeds, requiring crude protein content of more than 40%. Regular flushing, especially in the month before labor, to increase the amount of flushing, increase its water stimulation. When the water temperature is appropriate, select the abdomen to expand, soft, abdominal can see the obvious outline of the ovaries, gonads expand and red females, light pressure on the abdomen with male outflow of male sperm for oxytocin production. When using artificial insemination, the ratio of male to female is 2:1; the ratio of male to female of natural spawning and fertilization is 2:3. The commonly used drugs for oxytocic home fish can be used. One or two injections will do. When the water temperature is 22 to 23°C, the effect time is 12 to 14 hours. Artificial insemination method, we must pay attention to grasp the effect of time, accurately determine the estrus time of broodstock, timely catch broodstock for egg collection, sperm extraction, mixing evenly, make it fully fertilized. The hatching methods include natural hatching, debonding hatching, and non-sticking hatching. The commonly used hatching loops can be hatched in hatching tanks and small cages. The hatching water temperature is generally 17 to 28°C, and the optimum water temperature is 23 to 25°C. .
2, fry cultivation: fry pool area of ​​25 to 100 square meters, water depth 0.8 to 1 meter is appropriate. The fry stocking density is 1000 to 1500 per square meter. When the pool is at a proper time, the yolk sac of the fry disappears, and the swimming can be carried out in a timely manner when the swimming level is normal. Feeds for fry can be cooked with egg yolks or small horns and copepods. As the fish grows, you can feed leeches, chironomid larvae, leeches, maggots and various small fry, or feed them. Silkworm cocoon powder, pig blood, artificial feed, etc. It should be noted that fish fry of different ages cannot be mixed in the same pool. The bigmouth owl is a little afraid of light, so it's best to set a cover on the fry pool. The incubation time is 10 to 15 days. When the fry grows to about 3 cm, it is reared in separate ponds.
3, fish species cultivation: The body length of about 3 cm of summer fish species cultivated to 10? 12 cm large-size fish species, which lasted about 30-40 days. This stage is a critical period for the cultivation of fingerlings. The big oyster must experience the process of being forced to switch from eating live bait to eating artificial feed. At the same time, it is the period of the most severe mutual food. It should be noted that the transparency of the pool water is moderate, and when the water quality is clear, the self-mutilation phenomenon is the most serious. It is necessary to invest in the favorite feed of big oysters, and timely clear the pond and grading in separate ponds. After the fish species reaches 5 cm, artificially prepared transfer feeds, ie, artificial feed supplements with the addition of attractant, are to be fed. The basic components are fish meal, silkworm meal, pig blood meal, yeast meal, pancake meal and wheat. Lure attractants include fish gills, shrimp crab gizzards, and animal liver gizzards. Transfer process is 7-12 days. Feeding 2 to 3 times a day, feeding 15 to 20% of body weight. When 70% of the fish species have been able to ingest artificial compound feed, artificial compound feed can be completely fed twice a day. Compound feed ingredients requirements: Crude protein 42 ~ 48%, crude fat 8 ~ 10%, sugar 25 ~ 30%, crude fiber 6 ~ 8%, plus a certain amount of vitamins and inorganic salts. We must strengthen management and prevent diseases.
(d) Feeding of adult fish
To choose pure big-mouthed larvae for adult fish farming, distinguish them from the soil-borne larvae at the time of purchase. The upper leaves of the caudal fins of the bigmouth larvae are significantly longer than the lower leaves, and their body color is more yellowish-brown and gray-yellow, their colonies are active, and their foraging ability is strong. On the other hand, the upper and lower leaves of the caudal fins of the soil lice are long and black or dark. Dark green, scattered in the pool, inactive, poor feeding, slow growth, small individuals. There are many ways to raise large amounts of fish in different parts of the country, mainly in the following categories:
1. The main pond raising: The pond area is less than 5 mu, generally 1 to 2 mu, and the water depth is 1.5 to 2.0 meters. It is required to have sufficient water supply, convenient drainage and drainage, and it is best to use an aerator. The ponds were sterilized by clear tanks before the seeds were released. 800-1000 acres per acre seed, specifications for each tail 8-12 cm, feeding 140-150 days, then can develop into a fish with an average tail weight of more than 500 grams of fish, the survival rate of 85 to 95%. Can also be used with stocking a certain number of flowers, white large-size fish species, put 100 to 120 per acre, pay attention not to keep oysters, oysters, grass carp and other food-eating fish. Adult fish feed is mainly artificial compound feed, requiring crude protein 36? 42%, particle diameter of 3? 5 mm. Wherever possible, fresh live animal feedstuffs can be fed, including various wild fishes, domestic fish seedlings, tilapia larvae, animal viscera, earthworms, fly maggots, snail meat, and livestock entrails. The quality of these feeds is high, but the quantity is limited, which is suitable for large-scale breeding of small-scale farms or fishermen. The basic ingredients of artificial compound feed are fish meal, silkworm cocoon, blood meal, bean cake, rapeseed cake, corn and wheat, plus vitamin and inorganic salt mixture. Feeding with high-quality artificial pellet feed, the feed coefficient is 2 to 2.5, which takes about 150 days to reach the production level of 400 kg per mu.
2. Pond set-up: In the fish ponds, pro-fish ponds, and Daxie ponds where there are more small wild fish, it is possible to properly stock some large-mouth fish species. The amount of breeding depends mainly on the amount of feed fish in the water area. Usually, 20 to 50 species of fish with a body length of 12 cm or more can be released per acre of water. In this way, large-mouth bream adult fish weighing 0.5 to 1.5 kilograms per mu and 10 to 25 kilograms per mu can be harvested without reducing the production of main fish and increasing feed input. The provision of large oysters in fish ponds at home will not only affect the yield of the main fish, but on the contrary, the oysters can eat wild fish and sick fish to reduce the occurrence of fish competition and suppression of fish diseases. To increase production and income. Therefore, the method of rearing large oysters in fish ponds is of great significance. However, it should be noted that it is not appropriate to rely on raising fish to solve ponds of large-sized fish species in the coming year and it is not appropriate to breed large-mouthed fish. There are also ponds where the water quality is too fat, irrigation and drainage are inconvenient, and the family fish often floats without an aerator. It is also not suitable for mixed breeds.
3, cage feeding. Because the largemouth bream is artificially domesticated and cultured, it has a good ability to adapt to the cage environment and artificial feed. Therefore, the use of cages for largemouth larvae has developed rapidly in recent years.
(1) Net cage erection: Three-level cage culture methods are often used. That is, stocking 4 - 5 cm long fish species, first cultivated in a cage, grow to a certain size, into the second-class fish cage breeding, and finally into the third-level fish cage culture. The nets of the three cages are 0.6-0.8 cm, 1.0-1.5 cm and 2.5-3.5 cm, respectively. Net cages should be set up in relatively open, sunny, with certain wind waves or slow flow of water, water depth of 5 meters or more, transparency of about 1 meter, the water temperature of 22 degrees above the year for 3 to 5 months.
(2) Stocking of fingerlings: The seedlings that were reared in the same year were cultivated to 4-5 centimeters before being placed in cages of the first class. The density was 400 to 600 tails per square meter. After 15 to 20 days of breeding, the clearing box is sifted and the boxes are bred in different sizes. The fish species of more than 8 cm in size are reared at a density of 300 to 400 per square meter. When the fish species size reaches 16.5 centimeters, it is transferred to a secondary seed box and the density is 200 to 250 tails per square meter. When its tail weight reaches about 25 grams, it is transferred to a fish box and the density is 120 to 150 tails per square meter. If each year's fingerlings with a tail weight of about 400 grams are sold, only 30 to 50 tails can be stocked per square meter. In the case of the stocking density of the fish mentioned above, a 25-square-meter adult fish cage can produce 1500-2500 kg of large-mouthed adult fish.
(3) Feeding technology: According to the nutritional requirements of different growth stages of bigmouth larvae, 4 feed formulas are commonly used in production, namely, feeds for conversion, feed for fingerlings, feed for adult fish, and feed for autumn, among which the highest protein content is transferred. Food feeds amounted to 45 to 48%, and then declined as the fish grew up. The adult fish feed formula can have a crude protein content of 35%, including fishmeal 25%, peanut powder 18%, yeast powder 5%, fish oil 1.1%, corn powder 10.4%, compound amino acids 2%, and premix 2.5%. During processing, it is necessary to pay attention to smashing the raw materials as much as possible, and the quality of the adhesive is better, so as to ensure that the feed pellets are not loose in the water for about one hour, thereby improving the utilization rate of the large oysters.
In the cages, large mouth owls are raised. Individuals are fed in the middle layer of the water. Individuals are fed in the bottom layer. Small individuals love to eat quail and soft feed. Slightly larger individuals are willing to eat dry and hard granules. Feed; Regardless of the size and size of the squid, there is almost no habit of catching water on the surface to catch food, and it is better to live in the box weeks and 4 box corners. Therefore, a feed station must be set up in the cage. Generally, there is 1 square meter for 10 square meters, 1-2 for 25 square meters, and 20-30 centimeters away from the bottom of the net in the box. When feeding, the feed is sprinkled on the surface of the water above the feed table and swallowed by the big oysters as the feed pellets gradually sink. When the feeding amount is 5 to 10 cm in length, the daily feeding rate is 8 to 10% of the fish's body weight, and the daily injection is 3 to 4 times. When the total length is 10 to 13 cm, the daily feeding rate is 4 6%, daily shot 2 3 times; full-length after 23 centimeters, the bait rate can be reduced to 1-3%, daily feeding 1? 2 times, the last time every day feeding can be arranged at 10 o'clock in the evening Do it from left to right.
Cage rearing is generally carried out in May. It is reared until the end of October and harvested for more than 150 days. The survival rate can reach 70%. Each square meter cage can produce 65-100 kg of commercial fish, and the tail weight can reach 500. 700 grams.
4. Paddy field stocking: Practice has shown that big oysters can be used as the main variety in paddy fish farming. Paddy fields must be provided with adequate water sources, energy irrigation, drought-free days, flood-free flooding, and good water quality and pollution-free areas. The area of ​​the block is required to be around 1 mu. Before releasing the fish species, it is necessary to increase the height of the field hoe, excavate the fish ditch and the fish quarry, and build a fish stopping device. The size of the fish to be placed is large, and the fish body is strictly disinfected with 5% salt solution. It is also possible to mix some carp and grass carp species. During the breeding process, wild fish caught in other waters or low-value and low-value fish may be fed as feed, or these small fish may be minced into meat by using a meat grinder and mixed with other vegetable feeds to make flour. Bonded and mixed bait feed. If the scale of farming is large, full-grain pellet feed must be used to meet the demand for large-scale production. Water injection and replacement of new water should be done regularly to ensure fresh, live and cool water.
(five) fish disease prevention
Bigmouth bass has stronger disease resistance than many other fish, so there are not many common diseases. Relatively speaking, the bigmouth bass has a little more fish disease at the seedling stage. Commonly, there are white tip whitebait disease, small melon worm disease and hemorrhagic disease. At the stage of adult fish, it is easy to suffer from enteritis disease, print disease, and rickets. The causes of these diseases are often caused by poor disinfection of fish ponds, excessive stocking densities, failure to improve water quality in a timely manner, and feeding pathogens. Therefore, prevention should be the first priority. Once the disease has occurred, it should be promptly treated. Since the bigmouth bream is a fish without scales, it is more sensitive to various drugs than pelagic fish. Therefore, special attention should be paid to the use of drugs, and the amount used should not exceed the conventional amount. For drugs that are irritating and toxic, The amount should be smaller than the conventional amount, and it is more appropriate to use a small number of times. Such as treatment of white tip disease, if caused by trichodinosis, can be used per cubic meter of water containing 0.1 g of ferrous sulfate Quanchiposa; if caused by bacteria, 0.2-0.3 strong chlorine per cubic meter of water or bleach 1 g Sprinkle, or spray 25-40 grams of lime per cubic meter of water on the whole pool for 2-3 days.
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