Brief introduction and culture techniques of red tilapia

1. Biological characteristics of red tilapia: 1. Introduction, breeding and culture: red tilapia belongs to Perciformes, Perciformes, Cichlidae and Tilapia in fish taxonomy. According to the data, red tilapia was originally introduced from Israel by Taiwan Province of China in 1965 and attracted attention in Taiwan in 1968, constantly expanding the scale of culture. In October 1973, the aquaculture team in Japan organized by the former Ministry of Agriculture and Forestry and the Ministry of Foreign Trade received 229 fish fry from people of Chinese descent in Japan and introduced them into mainland China. This batch of fish fry was eliminated due to the large separation of offspring, the decline of growth rate year by year and the decline of promotion value. In 1981, the Pearl River Fisheries Research Institute re-introduced 110 3 cm red tilapia fry from Taiwan via Hong Kong, and 72 survived. This is an earlier fish species. After that, the scale of introduction and culture was continuously expanded through a variety of channels, so that the production of red tilapia was rapidly increased in the south, especially in Fujian, Guangdong, Guangxi, Hainan, Hubei, Yunnan, Jiangsu and other provinces, municipalities and autonomous regions. Relevant scientific research institutions in Guangdong, Fujian and other provinces carried out the breeding of improved varieties of red tilapia before 1990, and achieved good results. For example, the Fisheries Research Institute of Foshan City, Guangdong Province has used four years since 1986 to determine the genetic characteristics of red tilapia as the basis for breeding, taking body color, shape and growth as indicators, and adopting the method of comparing individual breeding with population breeding. The breeding of red tilapia introduced from Taiwan was studied, and the F5 and F6 generations obtained had obvious excellent characters. The proportion of red individuals was 75.8% and 80% respectively, and the growth rate increased by 10.87%, 16.73% and 12.4%, respectively. The population yield increased by 13.72%, 25.54% and 25.2%, respectively. The yield per mu of conventional farming is more than 300 kg. In recent years, small cage culture has been developed. in some areas of Fujian and other coastal provinces, the main species of culture is red tilapia. In 1998, Zhuanji Town, Jieshou City, our province conducted an experiment. In the river with an area of about 100 mu and a depth of 4-5 meters, three cages with a length of 6 meters, a width of 5 meters and a depth of 1 meter were set up, with a total area of 90 square meters. 7000 3-5 cm red tilapia summer flowers were bought from Fujian on July 8 and fed with eel pellet feed twice a day. After more than three months of feeding, the average body length is 25cm, the weight is 280g, the survival rate is 85.7%, the total production of fresh fish is 1680 kg, minus fish species and freight, feed fees, etc., a profit of tens of thousands of yuan. 2. Biological characteristics: biochemical genetic and cytological analysis show that red tilapia may be a hybrid variation between Mozambican tilapia and Nile tilapia. Its genetic relationship is close to that of Nile tilapia and its shape is similar to that of Nile tilapia. The body color is mainly red and yellow, the color is bright, it is very attractive, and it has both edible and ornamental value. Because of its body image of sea bream, the meat is delicious, so it is also known as "rainbow sea bream". The body of tilapia is flat, with 3-3.1 times of head length and 2.4-2.5 times of body height. The mouth is small, and the cleft mouth can not reach the edge of the eye. There are 16 hard spines of dorsal fin and 12-13 soft strips. There are 29-30 scales along the dorsal fin line. 3. Living habits: red tilapia can endure the water temperature of 8-42 ℃, and the suitable water temperature is 24-30 ℃. It can survive under the condition of low dissolved oxygen, and the phenomenon of floating head is easy to occur in pond culture, but generally it will not die in large numbers. Under the same conditions, the stocking density in the pond can be 2-3 times higher than that of the general famous fish. It also has a strong ability to adapt to salinity and can be cultured in seawater after gradual domestication. The natural bait of red tilapia is zooplankton and phytoplankton. Young fish feed on zooplankton and some green algae phytoplankton. When they grow up, they mainly feed on phytoplankton and organic detritus in ponds. Under the condition of artificial culture, fish meal, miscellaneous fish, silkworm pupa, bean cake, rice bran, wheat bran, vegetable leaves and all kinds of animal feed can be eaten. This fish has a large food intake and strong digestion and absorption capacity. Red tilapia seedlings in the pond after 4 months of breeding, if properly managed, the weight can reach more than 150 grams, up to about 500 grams before overwintering. Red tilapia is sexually mature in the year and can lay eggs after being raised for 150 days. When the water temperature is above 20 ℃, the mature male fish will dig their nests and reproduce, and the fertilized eggs will hatch in the mouth of the female fish until the larvae have the ability to move. Female fish do not eat during the breeding period, so it can be seen that there are differences in the growth of male and female fish. If artificial reproduction is carried out, the young fish should be separated in time to avoid being swallowed by the parent fish. When the young fish are a little bigger, they are easy to kill each other if the density is too high. Like several other tilapia being popularized and cultured, red tilapia is a species with few diseases, easy to raise and grow fast. 2. Culture of red tilapia 1. Pond culture ① pond conditions: red tilapia, like other tilapia, do not have high requirements for ponds. Generally, it is better to take less than 5 mu, which is mainly convenient for management and starting to catch. The depth of the pool is 2 meters, and the depth of water is about 1.5-1.8 meters. The water quality is good and can be replaced and injected. The seedlings should be cleaned and disinfected, fertilized and fattened before they were put into production. ② fingerling stocking: according to the requirement of total yield of 500kg to 600kg per mu, the main culture density can put 3000-4000 summer flowers per mu, or 1500-1800 overwintering fish with 10-20g overwintering fry. The autumn tail weight of the former can reach 150-200 grams, while the latter should be about 400 grams. It is better to enlarge the fish. Another 200-300 fish species such as common carp, crucian carp, silver carp and bighead carp are raised. The mixed culture density is mainly "four big domestic fish", with 200-500 overwintering red tilapia species with a tail weight of 5-50 grams. Autumn pool specifications 250-500 grams. The release of fish species should be carried out when the water temperature is stable above 18 ℃. ③ feeding and management: in the early stage of feeding, the size of fish species is small, and they like to eat in groups, so we should pay attention to feeding concentrate fodder with high nutritional value to promote the rapid growth of fish species. In the high temperature season, due to the high density of fish and more bait fertilization, floating heads are easy to appear. It is necessary to change water frequently and add new water. If equipped with an aerator, it is necessary to start the machine to increase oxygen in time. In the later stage of culture, that is, from August to September, some fish have reached the specifications on the market, so it is necessary to start fishing in time, one is to use the fishing off-season to enter the market and increase the price, and the other is to reduce the density of pond fish, do a good job of late management and improve the specification. 2. Cage culture ① sets water conditions: generally, the water quality is fresh, the water surface is open, the water depth is more than 2 meters, small lakes, reservoirs, rivers and ponds without pollution can be equipped with cages, preferably in places with micro-running water, requiring the bottom of the box to be 30-50 cm away from the bottom of the water. ② cage specifications and settings: the cage for breeding red tilapia is smaller, 10-30 square meters for more, it is best to develop 1-4 cubic meters of small cage culture red tilapia, setting and management are convenient. There should be a distance of 3-5 meters between the two cages, the arrangement of the cages should be perpendicular to the direction of the current, and there should be a distance of more than 10 meters between the two columns. ③ release density and specifications: traditional cages are generally dozens of square meters, with dozens of fish species per square meter. The small cages promoted in recent years can store 200-600 fish species per cubic meter according to different water conditions and management levels. The size of fish species should be larger, the size of fish species in small cages should be about 50 grams per tail, and the tail weight on the market in October is 400-500 grams. ④ feeding and management: in the waters where the water quality is thin and transparent, cage culture is mainly fed with pellet feed. The feed should be nutritious, with a protein content of 28% Mel 32% and a crude fat content of about 5%. In addition, certain vitamins and minerals should be added. Feed 2-3 times a day, according to different water temperature and different developmental stages of the fish, the daily feeding amount is 2% of the body weight of the fish.