The present situation and diseases of California bass culture are introduced in detail, and it is recommended to collect them!
I. Basic information
California perch with flat side and spindle shape; The back meat is slightly thick, dark green and green on the side; Dense black spots are scattered on the back of the head and arranged in strips; The body is covered with fine scales and the mouth is very big. The teeth are fluffy, thin and sharp. Hydrate, native to fresh water lakes in the United States, was introduced to China for aquaculture from 1983. After artificial domestication, it can grow normally in brackish fresh water below 65438 0%, and likes to live in clear water layer and waters with aquatic plants.
Second, the introduction of origin
Native to the Mississippi River system in California, USA, it is a famous carnivorous fish with delicious meat, strong disease resistance, rapid growth, easy catching and wide temperature range. Guangdong, Shenzhen, Huiyang, Foshan, Zhejiang and other places also introduced California bass fry on 1983, and artificially propagated successfully on 1985. The propagated fry have been introduced to Jiangsu, Zhejiang, Shanghai, Shandong and other places, and have achieved good economic benefits.
Characteristics and culture of California bass
Features: The most prominent advantage of California bass is its fast growth. The fry propagated in that year can grow to 0.5 kg, reaching the market specifications. California bass can not only be intensively cultured in ponds with a single species and an yield of more than 2,500 kg per mu, but also be mixed with other species. This is because California bass is a typical carnivorous fish. It can kill two birds with one stone by mixing a certain number of California bass in the traditional four major fish or other famous new species, which can effectively control the excessive reproduction of wild fish, shrimp and tilapia in fish ponds.
Pond culture: The conditions of bass culture pond require sufficient water, convenient irrigation and drainage, no leakage, water depth of 2-2.5m, good water quality, no pollution, ventilation and light transmission, and loam as the bottom material. Because perch likes to live in fresh, non-turbid still water environment and moves in the middle and lower water layers, it has the habit of occupying habitat. The suitable growth water temperature is 12-30℃. I like alkaline ponds, and PH 7.5-8.5 is the most suitable. The area of a single pond mouth is about 5~8 mu. 50 ~ 80 kilograms of quicklime per mu is spread all over the pond, then dried in the pond for 3~5 days and injected with fresh water. Cultivate the water color with fertilizer before the seedlings go into the pool.
Fourth, the status quo of aquaculture
According to statistics, in 20 18, the aquaculture output of freshwater bass (mainly California bass) in China was 432,000 tons, mainly distributed in seven provinces including Guangdong, Zhejiang, Jiangsu, Jiangxi, Sichuan, Hubei and Fujian, accounting for nearly 94% of the total national output, of which Guangdong accounted for 60%. The distribution of California bass culture is as follows.
Guangdong: Aquaculture is mainly distributed in Foshan City, Pearl River Delta, mainly in intensive pond culture. According to the investigation, in 20 18, the aquaculture area in Guangdong was 80,000 mu and the output was 258,400 tons. Among them, there are 33,000 mu of California bass cultured in ponds in Shunde District, Foshan City, mainly distributed in Liu Le, Xingtan, Lecong, Longjiang and Jun 'an towns. Nanhai District of Foshan City has more than 20,000 mu, mainly distributed in Jiujiang Town. The average yield of California bass in Shunde and Nanhai is about 3 tons per mu, and the highest yield can reach 6 tons. According to this calculation, the aquaculture output of California bass in Shunde and Nanhai is nearly 200,000 tons.
Jiangsu: Aquaculture is mainly distributed in Nanjing and Suzhou, mainly in ponds. In the past, the area of cage culture in rivers and lakes was large, but due to environmental reasons, cage culture has been greatly reduced. According to the investigation, there are more than 30,000 mu of California bass cultured in ponds in Wujiang District of Suzhou, and about 6,543.8+0.5 million mu in Gaochun District and Lishui District of Nanjing, with an average yield of more than 654.38+0 tons per mu. Based on this calculation, the total output is about 40 thousand tons.
Zhejiang: In recent two years, the output of California bass culture in Zhejiang Province has been increasing, and the culture is mainly distributed in Hangjiahu area. According to the introduction and data, there are more than 20,000 mu of California bass pond culture in Huzhou alone, and the aquaculture output has exceeded 50,000 tons in Jiangsu. It is the second largest bass culture province in California.
In addition, Jiangxi and Sichuan used to breed California bass in cages, but now they have basically withdrawn from cage culture. At present, there is no centralized breeding area in Jiangxi, and the actual output is not much; Pond culture in Sichuan is concentrated in Chengdu, Mianyang, Deyang, Panzhihua and other cities, with an average output of 1 ton ~ 1.5 ton, and the actual total output is about 30,000 tons. The scale of aquaculture in Fujian is very small, and it is in the trial breeding stage, mainly concentrated in the suburbs of Zhangzhou City. Moreover, for the fry introduced from Taiwan Province Province, although the amount of culture in Hubei Province is small, the culture output of California bass has been on the rise in recent two years, with great potential.
Verb (abbreviation for verb) inventory mode
Shandong, northern region: northern region, spring festival evening, early winter. Large-scale bass fry should be selected in California, with 20-50 fry 1 kg, and the fry should be released from the end of April to the beginning of May. Fishing in September -65438+ 10. The stocking density is 2500 ~ 3000 fish/mu, 300 fish/mu, 30 silver carp/mu and 30 silver carp/mu, and a small amount of herring is also raised. The yield per mu reaches 2000-2500 Jin.
Two Lakes Region: The main culture method of California bass is interplanting a small amount of other fish in the main culture pond. There are two sources of seeds: introduced from Guangdong and bred locally from the end of March to the beginning of April. The stocking density is 2500 ~ 3000 fish/mu, 300 fish/mu, 30 fish/mu and 30 fish/mu. The yield per mu reaches 2000-2500 Jin.
Pearl River Delta Region: The species density of California perch is about 6000 -8000 per mu. In addition, bighead carp 100, crucian carp 400-500 and catfish 1500-2000 are polyculture. There are 5000- 10000 Jin per mu.
Six, disease encyclopedia
1, rot disease
(1) Symptoms: the trunk muscles are deeply rotted, and in severe cases, the abdominal cavity is perforated, and internal organs can be seen, or the muscles above the lateral line are all missing; The diseased fish gills are pale white, with flabby muscles and strong fishy smell. Most of these sick fish are not infected with parasitic diseases.
(2) Pathogen: A large number of rod-shaped living bacteria are common in the focus, and occasionally suspected pathogens can be isolated from organs, but the proportion of pathogens infecting organs is low; The positive rate of iris virus in posterior kidney and muscle is extremely high, reaching over 95%, with a large amount of virus, mostly strong positive; Therefore, it can basically be considered as iridovirus disease.
(3) Epidemiological characteristics: The disease mainly infects California bass with a total length of 10cm or more, and adults can also get sick, but it mainly infects California bass with a total length of 15-25cm. After the rainstorm, the incidence rate is high, and it is also common in ponds with long-term poor water quality (ammonia nitrogen and sub-salt exceeding the standard for a long time) and improper feeding (using inferior feed, overfeeding, etc.). ) and poor management.
(4) Prevention method: Clean the pond thoroughly with quicklime, and spray chlorine dioxide and iodine preparation alternately at regular intervals to disinfect the whole pond. Vitamin C is added to the feed, and the addition amount is 1‰-3‰ of the weight of the feed fish. It can be prevented and controlled by external disinfection and oral administration (water disinfection and oral antibacterial drugs). During the high temperature period in summer, some preventive measures can be taken, such as increasing the water depth in aquaculture ponds, reducing the feeding amount, ensuring the quality of bait, not feeding spoiled and unclean bait, and adjusting the water quality environment, so as to maintain the stability of the water quality environment and reduce the occurrence of diseases caused by stress.
2. Tattooing disease (iris virus disease)
(1) Symptoms: The superficial ulcer on the body surface is punctate or massive, which looks like a beetle bite at first glance, but after careful observation, there is no worm, and a large number of active bacteria can often be seen under the microscope; The gill cover of some diseased fish is red and swollen or even ulcerated, and the base of gluteal fin and pectoral fin is congested and red; Anatomy occasionally shows white spots or yellow atrophy of the liver.
(2) Pathogen: Most of these diseased fish have not detected parasites; Lively liver bacteria are often seen in the lesions, but those suspected to have pathogenic bacteria are often not separated from the internal organs; The positive rate of iridovirus in the posterior kidney and cheeks is extremely high, reaching more than 95%, and the virus amount is large, mostly strong positive. So it can basically be considered as iridovirus disease.
(3) Epidemic characteristics: the disease mainly harms fish with a total length of about 8- 15cm. Fish ponds with excessive density are easy to get sick, and the incidence rate is extremely high within 10 days after the fish pass through the pond, often mixed with Flavobacterium columniform, with very rapid onset, extremely high mortality, difficult treatment, long treatment period and even loss of more than 80%; This disease can also harm adult fish.
(4) Prevention and treatment methods: At present, there are no effective prevention and treatment measures, and the general treatment effect is not good, and the condition will be alleviated when the water temperature drops.
3. Nocardia disease
(1) Symptoms: The body surface is covered with flowers, the wound is bright red, or there are deep sores on the body surface, and milky pus is squeezed out; Anatomy shows that there are white nodules in the liver, spleen and kidney, and giant cysts are common in the posterior kidney. Cut the muscle and you can see the gray nodules.
White nodule
(2) Pathogen: The diagnosis can be made by taking the focus or the pus of the posterior kidney and tabletting it for microscopic examination.
(3) Epidemic characteristics: the disease mainly infects old fish in ponds. Because of weak constitution and poor water quality in ponds, Nocardia can infect the immune organs of sick fish. The treatment of this disease is very difficult, and the high temperature period is fast and urgent. Once it occurs, the losses are often very heavy.
(4) Prevention and treatment methods: external disinfection and internal administration (water disinfection and oral administration of antibacterial drugs) are adopted for prevention and treatment. In addition, during the high temperature period in summer, some preventive measures can be taken, such as increasing the water depth of aquaculture ponds, reducing the feeding amount, ensuring the quality of bait, not feeding spoiled and unclean bait, and adjusting the water quality environment, so as to maintain the stability of the water quality environment and reduce the occurrence of diseases caused by stress.
4, rotten mouth and rotten tail disease
(1) Symptoms: superficial ulcer in the mouth or tail with more organic adhesion; Sometimes there are superficial ulcers on the back and abdomen.
(2) Pathogen: A large number of columnar Flavobacterium (long rod, swinging at one end, often forming cactus or cactus colony) can be seen in the mucus and scales at the focus under the microscope. It is sensitive to pH value, and its growth is inhibited when the pH value of water reaches 8.0 or above). The disease is caused by Flavobacterium columniformis infection.
(3) Epidemic characteristics: it mainly harms the new fish in that year. It should be pointed out that Flavobacterium columnar mainly invades from the body surface, forming body surface lesions, but it can also invade liver, spleen, kidney and other internal organs.
(4) Prevention and control methods: thoroughly clean the pond (using quicklime to clean the pond), and use mild disinfectants such as iodine preparation to disinfect the water body in time after heavy rain or "white rain"; Usually, beneficial bacteria such as lactic acid bacteria and Bacillus are applied regularly to occupy the niche; And the use of appropriate trace fertilizers to maintain the appropriate fertility of water bodies and maintain the weak alkaline pH of water bodies are all effective preventive measures. Follow the treatment plan of external elimination and internal medicine.
5. Hydromycetes
(1) Symptoms: The aquatic fungus California bass swims out of the colony on the water surface, and the fish body is white catkin-like in the water, resulting in loss of appetite;
(2) pathogen: water mold on the body surface;
(3) Epidemic characteristics: it is easy to occur when the water temperature is low, mostly in winter and spring; Especially after the fish is damaged, it is easy to happen. It is very harmful to California bass fry and can cause a large number of deaths.
(4) Prevention and control methods: ① Be careful when handling fish, and try to avoid fish body injury, which can effectively reduce mold infection; (2) When the pond becomes ill, salt with a concentration of 4 g/m3 and baking soda with a concentration of 4 g/m3 can be sprinkled all over the pond.
6, wheel disease
(1) Symptoms: California bass suffering from rotifer will swim by the pond alone, with dull body color and slow movement, and will turn over and over. Rotifers are mostly parasitic on fish gills. When the gill cover is opened, more mucus can be observed on the gills, and the body can be seen sliding back and forth like a wheel when the gill silk is taken for microscopic examination.
(2) Pathogens: rotifers and rotifers;
(3) Epidemic characteristics: it is the most popular from February to June, and the suitable water temperature is18 ~ 29.5℃; Harmful to fry and fingerling. The disease spreads quickly, the infection rate is high, the infection intensity is high, and it is easy to get secondary infection.
7. Cucumber disease
Symptoms (1): The diseased fish is emaciated, its body color is black, it swims slowly, the skin mucus on the gills and body surface increases, white cysts are produced on the skin and body surface on the gills, and a large number of small gourds can be seen under the microscope;
(2) pathogen: pumpkin;
(3) Epidemic characteristics: it is most popular in April-May and August-September every year when the water temperature is 15-25℃, which is harmful to fry and fingerling;
8, anchor head withering disease
(1) Symptoms: There are red spots on the body surface, and the insect body can be seen after careful observation;
(2) pathogen: anchovy;
(3) Epidemic characteristics: it can harm fish of all ages, with high infection rate, strong infection intensity and long epidemic season. Anchorage Sparus can breed at the water temperature of 12 ~ 33℃, so it is mainly popular in summer.
9, calicivirus
(1) Symptoms: After being infected, California perch larvae parasitize in clusters on the skin, gills, fins and other places of the fish, which often causes tissue inflammation and leads to a large amount of mucus secretion, and the adherends on the body surface and fins are cotton wool; The fish body is thin and black, and the fry moves abnormally, that is, floating on the water or swimming slowly, and it is difficult to breathe, such as floating the head, which can lead to the death of the fry in severe cases; Microscopic examination showed a large number of calicivirus;
(2) pathogen: calicivirus;
(3) Epidemic characteristics: It is common in the breeding period of California bass fry, and often occurs in the aquaculture water with high culture density and high organic matter content.
10, flower liver disease
Symptoms (1): There are no obvious symptoms on the body surface, and the liver is red, white and yellow-red when laparotomy is performed;
(2) Pathogen: The cause of liver flower may be a single diet, lack of vitamins, or poor feed quality, which can not meet the nutritional needs of California bass growth.
(3) Epidemic characteristics: It is more common in ponds with poor feed quality and high feeding rate after domestication of California bass.
(4) Treatment plan: It is difficult to treat the liver without changing the feed. If the liver injury is not serious, lowering the water temperature will help improve the liver condition. It is suggested that the pond should be dug deep in the second year and the feed with good quality should be selected.
In addition, 40 kg florfenicol 100 g can be fed, and 100 g doxycycline can be added in severe cases. However, if California bass is fed with chilled ingredients, the effect is not good, so farmers usually use feed mixture when they encounter diseases.
Remarks: The prevention and control methods of parasitic diseases of California bass are basically the same as those of common domestic fish, so I won't repeat them here. In fact, the disease prevention of California bass culture should pay attention to density, environment and breeding.
1. Controlling stocking density: Due to the limited capacity of the pond, the stocking amount of fry in the pond is directly proportional to the economic benefits within a certain range, but after the maximum fish carrying capacity of the pond is exceeded, blindly increasing the stocking amount of fry is often not worth the candle.
2. Cultivate good water quality: The author found that in all ponds with good water quality, the incidence of metabolic disorder of California bass is less, even if the incidence and death are relatively few, it can be well controlled. On the contrary, ponds with poor water quality have higher morbidity and mortality. Therefore, in the hot season, attention should be paid to the management of water quality, with emphasis on detoxification and water transfer.
3. Scientific feeding: California bass should also pay attention to the feeding amount when eating normally to avoid excessive feeding. When the weather is bad, reduce or not feed. Choosing the right ingredients is a prerequisite for the success of California bass culture.