First, biological characteristics
(1) The "jianghu status" of South American white shrimp
Penaeus vannamei is taxonomically belonging to the phylum Arthropods, Crustaceans, Decapoda, Swimming suborder, Shrimp family, Shrimp genus, and shrimp subgenus.
Shrimp are actually relatively inferior organisms. In general, the more inferior organisms are, their resistance to disease and the ability to resist changes in the external environment are also relatively poor. Therefore, the shrimp of Penaeus vannamei is not so easy to raise. It's hard to predict the problem it's facing, and we can't realize it's sick until it has some symptoms. For example, enteritis, enlarged liver, redness of the liver, etc.
I habitually compare shrimp to "bugs." Its low level also affects its relatively short life cycle. Short-term breeding can achieve the specifications of the market, the cultivation of finished shrimp, which is indeed quite beneficial for investment, but the good price of shrimp is not easy to raise, so shrimp farming is a "high efficiency, high risk" industry, investment is risky, shrimp farming needs to be cautious.
(2) The "appearance value" of South American white shrimp
Adult shrimp can reach a maximum body length of up to 23 cm, the carapace is thinner, the normal body color is white and transparent (or light blue-gray), and the large tentacles are blue-blue [If you find that the large tentacles of shrimp are red, there are many reasons for this problem, and I'll talk about it later]; There are no markings on the whole body, but if you look closely, you will find that the shell of The Penaeus vannamei is densely covered with many small spots, especially in juvenile shrimp of 2 to 5 cm; The foot is often chalky,000, so it is known as the white-legged shrimp, the white-limbed shrimp.
(3) The "life style" of South American white shrimp
Penaeus vannamei is native to the Pacific coast of South America. During the day, it is usually quiet at the bottom of the pool (sometimes even the abdomen or the whole body is hidden in the mud and sand), and at night it is frequently active. This is what we call "day and night out", which is why shrimp feeding is fed more in the evening meal.
The natural habitat is a sericine seabed with a water depth of 0 to 70 meters;
This shrimp has a mild temperament, and under experimental conditions, it is rare to see mutual mutilation between individuals. Because of its easy-going nature, the yield of this shrimp will generally be relatively high, unlike giant river prawns or crayfish that kill each other in a state of starvation.
Adult shrimp mostly live in coastal waters closer to the shore, while juvenile shrimp prefer to forage in the bait-rich estuarine area. When we are feeding, especially when the shrimp size is large, the shrimp generally have the habit of cruising along the shore, which is a normal phenomenon, do not be surprised.
Regarding molting, there are many influencing factors. Including environmental factors, human factors, nutritional factors, etc. In the case of stable water environment, sufficient dissolved oxygen, and sufficient nutrition, the molting shell of shrimp will be advanced. Molting shells are mostly in the first half of the night, when the water temperature of 28 degrees in the seedling stage, about 30-40h molting once;
1-5 grams of juvenile shrimp molt once every 4-6 days; the time interval between adult shrimp molting is about 14 days;
Strong adaptability to environmental mutations, can be away from water for a long time without dying;
It is also very resistant to hunger and can survive for about 30 days in the case of complete food stopping.
Water temperature requirements: the appropriate water temperature is 16-35 degrees, the most suitable temperature is 25-32 degrees. Studies have shown that 1 g of juvenile shrimp grows the fastest at 30 degrees of water temperature. 12-18 grams grow fastest at water temperature of 27 degrees.
The smaller the individual, the weaker the ability to adapt to changes in water temperature. When the water temperature is less than 15 degrees, the shrimp will reduce or stop feeding. If the water temperature is less than 9 degrees, it is lying on the side or dying.
Salinity requirements: belong to the broad salinity shrimp; the fastest growth in brackish water, 1-2 weeks before harvesting shrimp should gradually increase salinity; the adaptation range of 5-45 ‰; the best salinity in 10-25 ‰; in the range of salinity, the lower the salinity, the faster the growth; the salinity measurement with salinity or hydrometer;
Water dissolved oxygen requirements: different body lengths of individuals to tolerate low dissolved oxygen has differences, the larger the individual, the worse the ability to tolerate low dissolved oxygen; artificial breeding, not less than 2mg/l; too low will affect the shrimp molting, affecting shrimp feeding, growth, and even hypoxia death; when dissolved oxygen is greater than 5mg/l, growth is fast;
Ph requirements: weak alkalinity is good; preferably in 7.8-8.6. Generally, 14-16 hours is the highest ph of the day; too high ph will enhance the toxicity of ammonia nitrogen and increase the toxicity of chlorine in water; too low ph will enhance the toxicity of nitrite and hydrogen sulfide;
Ammonia nitrogen content requirements: not more than 0.6mg /l is good; the indicators of the seedling stage can not be too high, which will affect the survival rate of the seedlings, too high, and the test seedlings cannot be tried.
Nitrite content requirements: controlled within 0.05 is better; this is more difficult, especially in the later stage, but as long as the shrimp can adapt, the high point of nitrite is fine.
Transparency requirements: 30-40cm in the early stage; 30-60cm in the middle and late stages;
Water color requirements: yellow-green, tea brown as well;
(iv) Its requirements for eating
It is an omnivorous species; under artificial breeding conditions, it will still eat feed during the day, but its feeding behavior is greatly affected by the close stimulation of feed. The feeding method of multiple meals a day is much faster in terms of growth rate than the feeding method of 1-2 meals a day; (the principle of small number of meals)
In terms of nutritional requirements, animal-based bait is the mainstay; the demand for food protein is low. The proportion of protein in the bait is more than 20% enough; the proportion of protein in the feed is 35-40%; the food with too high protein has a negative effect on improving the growth rate and breeding yield of Penaeus vannamei in South American white shrimp.
The curing efficiency of the bait is relatively high, 3-5% of the daily feeding amount; the shrimp gastrointestinal tract is developed and bulimia; under normal circumstances, the bait amount is about 5% of its body weight (wet weight); 1.5 hours after feeding, check the residual bait situation of the bait table (basically no remaining feed) and the shrimp stomach fullness (up to 70%);
25-35% of the feed is fed during the day and 65-75% at night;
(5) Molting and growth
Shrimp grow through molting; molting is not only a sign of the developmental metamorphosis of Penaeus vannamei, but also a necessary stage of individual growth;
Freshly molted shrimp are weak and do not eat, and are most vulnerable to attacks from their kind or predators. Juvenile shrimp take about a few hours to harden the new skin, while prawns can take 1 to 2 days.
Before molting: Absorb nutrients, store energy
Just after molting: the carapace is still soft; in a short period of time, the shrimp absorbs water and expands, growing rapidly;
After the molt is completed: absorb nutrients, store energy; prepare for the next molt;
Molting of shrimp is mainly regulated by endocrine hormones in the body. By removing the unilateral stalk of the shrimp, or under the influence of environmental factors and nutritional conditions, low salinity and high water temperature will increase the frequency of molting, and sudden changes in the farming environment or the use of certain chemical drugs will also stimulate molting. Nutritionally balanced shrimp molting will be frequent; molting is carried out at night or in the early morning, for a short time, 10-15 minutes;