<b>Spilirus species was introduced from Saudi Arabia in 1981 and is known abroad to be cultured at 35‰ salinity (provided by Huang Jiafu</b>).
Tilapia belongs to the family Osteichthyes, cichlidae (or Cichlidae), or Cichlidae, of the order Pecirformes, and there are about 100 species. The classification of species of cichlids is difficult and controversial. Some literature has classified various cichlids as the genus Thilapia in general. The most widely accepted is the taxonomy of Trewavas (1982), which divides the fish into non-crucian carp (Tilapia, e.g., T.zillii, T.rendalli, T.congica, T.guineensis), slug non-crucian spp. (Sarotherodon, e.g. S.galilaeusgalilaeus, S. melanothernmelanothern) and oral-hatched non-crucian carp (Oreochromis, such as O. niloticus, O.mossambicus, O.aureus, O. mortimeri) and other 3 genera.
Taiwan introduced Wu Guo fish in 1946, after the improvement of the species, the aquaculture area and output expanded rapidly, in 2001 the output has exceeded 80,000 tons, the output of more than 67,000 tons in the past ten years. In the past, Wu Guo fish was mainly sold domestically, and only began to be exported since 1993, the total production capacity of Taiwan Wu Guo fish in that year was more than 50,000 tons, and the foreign sales volume was about 10,000 tons, and then the foreign sales volume increased year by year, and the foreign sales volume in 2003 has reached about 40,000 tons, accounting for 47% of the total production.
<b>Statistical chart of Wu Guo fish in Taiwan, China</b>
Due to its reasonable price, year-round supply, moderate taste and ease of cooking, wuguo fish became the eighth most popular seafood in the United States in 2004, and many fast food chains sold wuguo fish, and the original export of wuguo fish was frozen whole fish from Taiwan, China. The U.S. market also loves Kureko fish fillets, which include fresh or frozen fillets in different sizes and packages.
<b>Water test selected breeding seawater Wuguo fish</b>
At present, the problem of shrinking freshwater resources and strata sagging in the aquaculture industry is becoming increasingly serious, and the marine culture of Wuguo fish has development prospects, compared with freshwater Wuguo fish, the biggest advantage of seawater Wuguo fish is its better taste and meat quality, and the price is also higher. Zeng Fusheng, a researcher in the aquaculture group of the Aquatic Products Experimental Institute of the Agricultural Committee, pointed out that although there are also salt-tolerant seawater Wuguo fish strains in Taiwan, it is difficult to promote them due to slow growth rate, long breeding time and high breeding costs. The team of the Institute of Water Experiments used gene marker-assisted breeding technology to improve the shortcomings of poor growth by cross breeding from the existing breeding species of Wuguo fish in Taiwan, aiming at the key points of seawater Wuguo fish breeding - growth and salt tolerance traits, and then selected Wuguo fish with excellent body size and Nile blood, after seawater domestication, and then carried out broodstock breeding according to body size and body color generation by generation, establishing a good seawater Wuguo fish strain, and the selected breeding seawater Wuguo fish strain was larger than the mosan bik strain. Using this strain as the genetic data of salt tolerance traits, it can be hybridized with the general Wuguo fish strain to obtain commercial high salinity resistant hybrid fry.
<b>The appearance and shape of the TFS strain of seawater Wuguo fish in the Fisheries Laboratory</b>
The water test institute is for the red Wuguo fish TsR and TsRn strains for seawater domestication, TsR strains are selected from the freshwater environment for several generations, belonging to the Mosan bik Wuguo fish bloodline, originally more able to adapt to the whole seawater, and even can breed in the seawater environment, but this strain grows slowly; and the TsRn strain is selected from the red Nile Wuguo fish, the adaptation to the marine environment is poor, but with the growth of the seawater environment adaptation also improves, but still can not grow in more than 25 ‰ environment for a long time. The Institute further selected the salt-tolerant red Wu Guo Fish TsRn strain and the seawater Wu Guo Fish TFS strain, and fully mated them, produced offspring and domesticated them in the seawater environment. Zeng Fusheng pointed out that the breeding results showed that the salt tolerance was related to the Wuguo fish strain, which had species differences, and the TFS of the seawater Wuguo fish played a decisive key role in the salt tolerance of the offspring, and the appearance of the anti-cross group (TFS×TsRn) was the appearance of the body color of the red background with black spots or black spots.
<b>Freshwater strains can only be cultured in brackish water</b>
In 2013, through the cooperation of the Fisheries Laboratory through technology transfer, the introduction of the water test institute's seawater Wuguo fish species TFS and the self-field red Wuguo fish strain (SDR) hybridization, after 3 years to breed with rapid growth genes can be generally cultured Wuguo fish, this year will be able to produce the first batch of 100,000 fish fry for commercial farming.
<b>Taiwan's Holy Snapper Aquatic Science and Technology cooperates with the Institute of Water Experiment to cultivate seawater Wuguo fish, and the hybrid offspring have three body colors of red, black and gray, which can be cultured in seawater with a salinity of 30 ‰</b>
Huang Chengxian, founder of Sacred Snapper Aquatic Science and Technology, said that although Wuguo fish is widely salinity, it is generally freshwater aquaculture to accelerate the growth rate and shorten the breeding period, even if the salinity is increased, it can only be up to 20 ‰, and the salinity of more than 20 ‰ will cause the skin of the fish to fester, and the Sacred Sea bream Seawater Wu Guo fish can adapt to the saltiness of 30 ‰ seawater.
<b>TFS× TsRn hybridizes 2-month-old offspring with a large number of dark dark spots</b>
Pure mariculture of Wuguo fish is a major breakthrough, because Wuguo fish is an omnivore, the demand for feed protein is low, and plant protein can be used, which is equivalent to "eating vegetarian" and will not destroy the ecology. Many of the cultured marine fish are carnivorous, such as grouper, which needs to be fed a large number of trash fish, according to its feed efficiency, 10,000 tons of marine fish require 50,000-60,000 tons of bait fish, and there are doubts about the shortage of marine food chains in large quantities. Even feeding artificial compound feed requires a high proportion of fishmeal and is also a burden on marine fishery resources. The omnivorous Wuguo fish cultivated in marine aquaculture will be expected to improve the situation of "farmed fish destroying the marine ecology".
Huang Yisheng, chairman of Shengsheng Aquatic Science and Technology, said that due to the fact that there is no growth data on commercial breeding of seawater Wuguo fish strains, but in the observation of the breeding and research and development stage, the use of Nile feed, feeding only one meal a day, from rice grain size seedlings to 1 catty is about 7 months, growing to 3-4 catties is about a year, some fish were stocked in February last year, and the size has reached 1.5-2 kg in May this year.
<b>The mother of this hybrid is red and the father is black</b>
Seawater salinity is high, due to the relationship of osmotic pressure, fish body cells to prevent seawater salts from infiltrating, cells in order to discharge too much salt to leave water, consume more energy, so growth is relatively slower than in the freshwater environment. However, the same fish, the meat cultured in the seawater will be more Q-bomb solid, no smell of earth, suitable for sashimi and steaming and other dishes, the value is also relatively high.
<b>Seawater Wuguo fry multiplication</b>
Wuguo fish is a fast-growing fish species, but before reaching the market size that is, sexual maturity, there are many shortcomings, first of all, sexual maturity is early, resulting in juvenile fish, is a major problem in the management of fish ponds, but also waste feed, increase costs; secondly, the fish body has to spend a lot of energy to produce sperm or eggs, so that the body growth slows down, resulting in an increase in the bait conversion coefficient; third, after reproduction, the quality of fish meat becomes poor, and the body is weak after spawning, resulting in increased mortality. Huang Chengxian pointed out that artificially farmed fish species in open water culture have the possibility of escape, the farm is currently trying to multiply the possibility of breeding, hoping to improve the problem of such breeding in the future, but in order to avoid doubts, the current initial promotion of land circulation water aquaculture ponds as the main object of cooperation, food safety standards to the EU.
<b>Sacred Seabream Aquatic Science and Technology uses the TFS strain of seawater Wuguo fish from the Aquatic Experimental Institute and the self-field red Wuguo fish strain SDR, which hybridizes to produce salt-tolerant and fast-growing seawater Wuguo fish, and the offspring have three body colors of red, black and gray</b>
Sacred snapper is carefully selecting cooperative breeders to promote this year's production of seawater Wuguo fish. Huang Yisheng pointed out that the promotion of seawater Wuguo fish is "heavy but not heavy", and the cooperative farms are mainly circulating aquaculture systems, although this fish can also be raised in sea cages, but it is not yet considered. Seawater Wuguo fish will develop towards industrial refinement, combined with fish breeding farms, circulatory system farms and terminal refrigeration processing plants, to improve quality and price, and to play a brand partition market for sustainable operation.
Huang Yisheng pointed out that China also has a salt-tolerant Tarabia variety, but the variety must be cultivated by artificial spawning, while the holy snapper can use natural spawning to breed hybrid offspring, the mainland strain can only reach 25 ‰ salinity, Taiwan seawater Wuguo fish can reach 30 ‰, the parents of the two are also different.
<b>Huang Chengxian (left), founder of Sacred Seabream Aquatic Science and Technology, said that the Wuguo fish strain of Sacred Seabream Seawater can adapt to the salinity of 30‰ seawater, and the right is Huang Yisheng, chairman of Sacred Seabream</b>
It is understood that the new salt-tolerant tilapia species Chinese mainland, named "Jiji", is based on the new tilapia (O. niloticus) new gitiftvariety (mother), Sarotherodonmelanotheron (Sarotherodonmelanotheron) as the father, and the new salt-tolerant varieties produced by hybridization can be cultured in seawater with salinity of 15‰-25‰. Jiji tilapia is a professor at Shanghai Ocean University Li Sifa who was selected and bred for many years and was published at the "6th Tilapia Industry Development Forum" in Nanning on November 9, 2009.
In 2010, the Hainan Academy of Oceanography and Fisheries sciences introduced salt-tolerant marine "Jiji" tilapia to study the polyculture technology of Penaeus vannamei in South America. South American white shrimp fry stocking density of 10,000 fish / mu, 15-20 days later, the average length of 2.17 cm of 40,000 tilapia fry, after more than 6 months of breeding, the average weight of "Ji Tuna" tilapia reached 398.6g, the survival rate reached 89.45%, and the mu yield of tilapia was 764.0kg.