A Preliminary Study on the Mariculture Model of Gili Tilapia

Gili Tilapia is a new breed that was selected by Shanghai Ocean University and confirmed by the Ministry of Agriculture on February 3, 2010. In order to discuss the marine aquaculture model of salt-tolerant tilapia jiri, in 2009, the use of 1,000 acres of ponds with a salinity of 20 to 25 for a one-year period of Gili tilapia monoculture And polyculture with shrimp trials. A preliminary exploration was made of the two modes of monotrophic seawater and mixed polyculture with prawn.

The monoculture mode focuses on the development of technologies for the production of high-quality seawater tilapia using discarded shrimp ponds, and studies the effects of tilapia release specifications and stocking densities on survival rates, growth rates, and aquaculture costs in seawater environments; the polyculture model focuses on Using tilapia as a biological regulator to study its mechanism and effect of improving water quality, improving sediment, inhibiting harmful bacteria, reducing shrimp diseases, increasing the survival rate and yield of shrimp, and eventually improving the comprehensive aquaculture efficiency of shrimp ponds. The test results will be introduced in the hope of providing basis for the development of large-scale popularization and application of the two models of monoculture and mixed polyculture of juvenile Gila.

First, test preparation

The tested Ji Li tilapia fry was transported by Tianjin Zhongjie National Tilapia Fine Seed Farm by air to Guangzhou in Tianjin in May 2009, and was then transported by car to the company's test site. After about 20 hours of transportation, the fish body has been weakened. Fish fry of different sizes were placed in two cages (4m1.5m1.5m) for raising, to restore constitution, and at the same time, adaptive feed for compound feed was carried out. After 7 to 15 days of intensive cultivation, until the body of the fish is about 3 to 5 inches. After the feeding is normal, the salt-tolerant acclimation is started, and the salinity required for the test pond is domesticated separately, and then put into the test pond for aquaculture test.

Second, experimental design

Polyculture of fish and shrimp under different salinities: 20 soil ponds with an area of ​​5 acres and a salinity of 25 tons and 20 ponds with an area of ​​5 acres. The Penaeus vannamei seedlings began to be stocked around May 10, and the stocking density of the seedlings was 60,000 tail/mu. After the shrimps were stable, on May 25, Ji Limiao was put in stocking. The stocking density was 30 fish per mu and a total of 6,000 fish fry were released.

Polyculture of fish and shrimp under different densities: select 5 acres of earthen ponds and 20 ponds with a salinity of 20 inches, and lay 5, 10, 20, 30, 40, and 50 tails per acre. Gradient seedlings, 4 ponds per gradient. The Penaeus vannamei seedlings began to be stocked around May 20, and the stocking density of the seedlings was 60,000 tail/mu. After the situation of shrimps was stable, Ji Limiao was put on June 5, and 3100 fish fry were released. During the experimental period, the feed of Penaeus vannamei was fed, and the daily feeding amount was the same as the normal feeding amount of the Penaeus vannamei culture pond with the same stocking density. Other daily management including water quality monitoring and regulation, drainage change, disease control, etc. is also the same as that of South American white shrimp monoculture pond. Observe the growth of fish and shrimp every 30 days until the shrimps are drained. Under single salinity, single breeding of Jiri fish: Select four earthen ponds with good conditions (injection and drainage are convenient and food-rich), with a total area of ​​16 mu. Two salinities, 20 and 25, were designed. Each salinity was designed to have a stocking density of 1,500 tails per acre and 2000 tails per acre. A total of 27,000 fry were released.

The monoculture test began on May 25, and 30 fish were randomly selected from each pool every 30 days during the rearing period. The body length and body weight were measured, and the daily feeding amount and the final harvested amount were recorded.

Third, breeding technology

1. Regulation of water quality: “Fish culture is water conservation” This is the talk of aquaculture production experience. Whether it can raise a good pool of water is the key to the entire aquaculture management process. Water quality regulation is based on the aquaculture water control technology of the South China Sea Fisheries Research Institute. The main operations are as follows: (1) Qingchi disinfection and fertilizer before watering: After the pond is flooded, 30 to 40 ppm of tea seed cake is used to kill the wild fish, and 1.5 to 1 is used simultaneously. 2ppm trichlorfon kills wild shrimps and crabs and other crustaceans. The biological carcass is removed the next day. After 3 days, 10-15ppm of bleach containing 30% of available chlorine is used to disinfect the pond water. 3 to 4 days after bleaching, the application of fertilizer culture water began. Old Pond: Apply "single-cell algae growth hormone" 2 to 3 kg/mu. New ponds: 25 to 50 kg/mu of fermented chicken manure and 2 to 3 kg/m2 of fertilizer masters. On the day after the fertilizer is applied or on the next day, 1.5 to 2 ppm of "enhanced probiotics" or "living bacteria" are applied to regulate water quality.

2 During the cultivation process, according to the changes in the water color of the ponds, top-floating microalgae nutrients “single-cell algae growth hormone” or “master fertilizer masters” will be maintained to maintain the stability of the pond water color, so that the transparency of the pool water will be maintained at 30-40 cm. Bacillus-degrading metabolites are periodically applied, and 0.5 to 1 ppm of "enhanced Lisin" or "living bacteria" are used to degrade metabolites every 7 to 15 days.

3 Salinity: In the breeding process, the salinity does not change too much. If the variation is too large, the growth rate will slow down and even result in the death of tilapia. Keep the daily salinity of the water body within 3 hours.

4 dissolved oxygen: 3 ~ 7mg / L, although tilapia can be tolerated below 1mg / L of low oxygen, but dissolved oxygen for less than 3mg / L for a long time, the state of the fish will not be normal, easy to disease. In pond culture, the dissolved oxygen in the water fluctuates day and night. Under normal weather conditions, the highest point of dissolved oxygen occurs at 2:00 noon. The dissolved oxygen in the upper layer is mostly in the state of supersaturation, and the lowest point is around 3 am, but if the water Too deep, the bottom of the pool is also called hypoxia during the day. The need to dissolve oxygen in the pond is ensured by the timely opening of the aerator.

5 water temperature: growth temperature of 15 ~ 32 °C; suitable degree of warmth 26 ~ 32 °C; optimum for 28 ~ 30 °C. Tilapia is under 12°C for a long time and it is vulnerable to freezing. 6 Ammonia: 0.1 to 0.3 mg/L. When the ammonia nitrogen is too high (greater than 1 mg/L), dissolved oxygen is no longer useful.

7pH value: 7.5~8.6. When the pH value is lower than 7.5, the whole pool is sprinkled with lime water. In the breeding process, we must maintain the stability of the water quality, do not change the water when the big row of large irrigation, it is necessary to change a few times, pond water and new water do not have much difference.

2. Feed and Feeding: Gili tilapia has a wide diet and can feed almost any commodity feed. In a pond monoculture experiment, it is fed with extruded tilapia and cultivated natural foods (phytoplankton with silicon). Algae and green algae are good, but they can also eat blue-green algae.) If the feed cannot be consumed within 20 minutes, the next feeding is reduced or paused until the fish eats normally. A feed station is set up beside the pond. The amount of feed to be fed should be based on the data on feeding, and should be appropriately withered according to fish dynamics, weather conditions, water temperature, and water quality. Feeding of feeds should not be too fast or too slow. Feeding too fast will result in wastage of feed and excess dirt. Feeding too slowly will lead to battles between the fishes and cause damage to the fins and eyes. In addition, improper feeding methods can cause large differences in group sizes. The feeding should be started sooner, then slow down, and observe the behavior of the fish. On the one hand, it is appropriate to increase or decrease the amount of feed according to the appetite, and on the other hand, see if the fish has abnormal behavior (such as shaking his head, floating head, swimming, etc.). Feeding time is 15 to 30 minutes each time, and the amount of feeding and the eating and drinking of the fish should be carefully recorded and stored.

The feed must be fed to “four settings”, ie timing: feed 4 times a day, the feeding time error must not exceed 30 minutes, and set point: set a feed station as a feeding point in places where fish are frequently found. After the fish are domesticated, they will all feed on the feed table. As the fish population increases, the feed table will gradually expand and increase. Quantitative: In addition to the special conditions such as rainy days, hot weather, and abnormal fish activities, the daily feeding amount must be relatively stable, and as the fish grows, it is fed. Quantity gradually increases, do not differ greatly; Qualitative: Feed must maintain good quality, do not cast odor, degenerate feed, at the same time after selecting a brand of feed, except for special circumstances, do not arbitrarily change to other brands of feed .

3. Disease prevention and control: Prevention and treatment of fish diseases is one of the important links in fish production, which determines the success or failure of breeding. In the process of mariculture of Gilia tilapia, the principle of “prevention first” has always been implemented. Through the good water quality and reasonable feeding and management, the fish's constitution has been enhanced. In the two years of cultivation demonstration, no fish medicine was used and no fish disease occurred. In terms of feeding and management, it is mainly to regularly add "Probiotics and Treasures" and various vitamins to the feed to achieve prevention and control of disease.

Fourth, the test results

1, different salinity polyculture

Shrimp ponds started shrimping in late September. Due to the use of electric capture technology, fish were also caught at the same time. The pond with an average salinity of 20 ‰ weighed 556 g and harvested 2672 kg of jish fish. The catch rate was 80%, equivalent to 26.7 jin per mu. The average pond pond weight of 25 ‰ was 573 g and the harvested fish was 2923 jins. %, equivalent to 29.2 kg per mu. The tilapia that were harvested were transferred to an unused pond after shrimps were kept and sold until the end of November.

Table 1 Average results of fishing in different salinity ponds


Fish weight

Fish yield per mu

Fish catch rate

Shrimp yield per mu

Shrimp recovery rate

Feed coefficient



556 g

26.7 pounds


1037 kg



Pai Tang 4


573 grams

29.2 kg


1106 pounds



Pai Tang 3

2, different density polyculture

Shrimp ponds started shrimping from late September to early October. Due to the use of electric capture technology, fish were caught at the same time. The caught tilapia was transferred to an idle pond after shrimps were kept and sold until the end of November. The results of the harvest are shown in the table below.

Table 2 Average results of fishing harvest in different density polyculture ponds

Stocking density

Fish weight

Fish yield per mu

Fish catch rate

Shrimp yield per mu

Shrimp recovery rate

Feed coefficient


5 tails/mu

585 grams

4 kg


998 kg



Pai Tang 1

10 tails/Mu

582 g

12 pounds


1243 pounds



20 tails/Mu

574 g

17 pounds


1026 pounds



Pai Tang 1

30 tails/Mu

563 grams

34 pounds


1236 pounds



40 tails/mu

532 g

42 pounds


1184 pounds



50 tails/mu


38 pounds


1056 pounds



Pai Tang 1

3, single salinity under different salinity

At the end of November, it began to be listed and harvested. A total of 25,332 kilograms of Ginger was harvested, equivalent to 1583 pounds per mu. The largest body weight female 763 grams, 835 grams male. The fishing results are shown in Table 3.

Table 3 Single-yield test harvest under different salinities

Pool number



Stocking density

Harvest specifications

Pond production

Recovery rate


3 acres


2000 tails/Mu


5582 pounds



5 acres


1500 tails/mu

598 g

7921 pounds



3 acres


2000 tails/Mu


4756 pounds



5 acres


1500 tails/mu

532 g

7073 kg


Third, analysis and discussion

1, fish and polyculture test

The experiment was conducted with shrimp as the main breeding object. As shrimp breeding cycle is generally 80 to 120 days, Yuan directly affects the growth of fish and shrimp disease is widespread. Although it is not directly transmitted to fish, once the occurrence of shrimp pond, Yuan is basically medicine-free. Doctors, and finally do the pond treatment Yuan led to a low recovery rate of the mixed fish, but we have collected more than 99% of the fish from the successful breeding shrimp ponds. This will improve the efficiency of shrimp ponds. It is obvious; for the bioregulators of Gilia, improving water quality, sediment quality, inhibiting harmful bacteria, and reducing shrimp disease research Yuan Yuan is subject to further time and condition constraints.

2. Monoculture test

Ji Li tilapia can adapt to harsh environment Yuan can survive in the case of water body pH drops to 6.5 and low dissolved oxygen. Yuan can make full use of discarded and newly excavated ponds for breeding. Yuan economic benefit is far away but the fish is not tolerant. The cold temperature Yuan Yuan cold temperature in the mid-November, under the attack of Yuan Shuiwen dropped to 12 benefits when Yuan Yu appeared frostbite and dead fish phenomenon Yuan directly affect the rate of recovery of the monoculture test.

3, sales

Ji Li tilapia after the trial was put on the market at the end of 2009. Due to its tender meat, the unique taste of Yuan is very popular with consumers. The price of the fish out of the pond was RMB 13/kg Yuan. In December, at the Kempinski Hotel in Shenzhen, RMB 78/kg was sold for more than 400 kilograms.

4. Prospect Analysis

According to the company's breeding trials in Yuan and sales, it can be seen that the new salt-tolerant species, Chili, is very suitable for polyculture in fish ponds or monocultures in southern China's seawater ponds, and fish and shrimp polyculture patterns are increasing in traditional soil ponds. Shrimp efficiency is good, Yuan Yuan, and Yuan Jili Tilapia's meat quality and taste The upper Yuan market is optimistic about Yuan, which has very good aquaculture promotion value and market prospects.

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