The larval cultivation process of Penaeus monodon is basically the same as that of Penaeus chinensis.

(1) Larval density The pond density of Penaeus monodon nauplii is determined by the nursery conditions and technical level, especially the feed and water quality conditions. Generally, small nursery ponds (10 to 20 m3) are stocked with 100,000 to 120,000 nauplii/m3, and large nursery water bodies (above 40 m3) are stocked with about 150,000 nauplii/m3.

(2) Water temperature control Penaeus monodon seedlings require water temperature above 25°C for larvae cultivation. The optimal water temperature is 28-30°C, with a maximum of around 33°C. High-temperature nursery can accelerate the growth of shrimp seedlings, shorten the nursery time, and increase the number of seedlings that emerge. However, high temperature nursery will affect the health of shrimp seedlings, and they are prone to illness during the growth process. When the water temperature is 27 to 29°C, the nauplii molt six times and metamorphose into ovarian larvae in about 36 to 50 hours. The _-shaped larvae take 3 to 5 days and become mysid shrimp larvae after three molts. Mysis shrimp larvae take 5 to 7 days and become larvae after molting three times.

(3) Larvae management

①Nauplii. Nauplii do not feed. But prepare food for the larvae. When they hatch into nauplii, insert Monocystis algae species and add nutrients: potassium nitrate 1 mg/L, sodium silicate 0.1 mg/L, and disodium hydrogen phosphate 0.1 mg. /L, ferric chloride 0.01 mg/L. The survival rate of nauplii is about 90%.

②_-shaped larvae. During the larval stage, diatoms can be cultured in the same pool or in separate pools to meet the feeding needs of the larvae. The density of Monocystis algae is not high, so you can supplement it with an appropriate amount of spirulina powder and yeast powder. Fertilized oyster eggs can also be fed directly, but do not overfeed to avoid water corruption. When throwing oyster eggs, the pond water needs to be exchanged about 1/3 every day. When the larvae develop to the 2nd to 3rd stages, feed the rotifers appropriately; at the 3rd stage, feed a small amount of scalded Artemia newly hatched larvae. The survival rate of _-shaped larvae is low, only 30% to 70%.

③ Mysid shrimp larvae. The food in this period is mainly animal-based, and a certain concentration of single-cell algae is maintained. Mainly feeding rotifers, Artemia nauplii, copepods, etc. If algae are cultivated in the same pond, filter the seawater with a 200-mesh screen and apply inorganic fertilizer. That is, potassium nitrate 100 mg/L, potassium dihydrogen phosphate 10 mg/L, sodium silicate (potassium) 1.0 mg/L, and ferric chloride 5 mg/L. Fertilizer is generally applied once every 2 days, and the water color should be brown. Single-cell algae are controlled above 50,000/ml. It can also be supplemented with supplementary feeding of Penaeus monodon artificial microcapsule series pellet feed or other shrimp artificial microcapsule pellet feed, yeast and other substitute feeds. Commonly used feeds include Japanese shrimp larval feed B.P, shrimp flakes, and Taiwanese Penaeus monodon postlarvae micro-pellet feed, shrimp postbaby, etc. The survival rate of mysid shrimp larvae is 70% to 80%.

④ Larvae shrimp. The larvae can metamorphose into larvae in 10 to 11 days, at which time they completely transform into postlarvae. The early stage of larval shrimp (P1~P5) mainly consists of Artemia nauplii, artificial microcapsule pellet feed, shrimp, crab, shellfish, etc. Later, it is expected that the larvae will develop to the P5~P10 stage and have benthic habits. The larvae like to eat large animal bait. At this time, fish, shrimp, shellfish, cuttlefish meat or artificial microcapsule pellet feed can be completely fed. The feeding amount is equivalent to 200% of the shrimp body weight, that is, the daily feeding amount is about 10 to 30 grams per 10,000 larvae. It is advisable to eat small amounts and frequent meals when feeding. The survival rate of juvenile shrimp larvae is about 80%. If P20 leaves the pond, the survival rate of juvenile shrimp larvae is about 60%.

(4) Water quality control Water quality directly affects the health and metamorphosis of larvae. Penaeus monodon larvae have strict requirements on water quality, mainly changes in ammonia nitrogen, dissolved oxygen, pH and other factors.

①Ammonia nitrogen. Non-ionized ammonia in ammonia nitrogen has a toxic effect on larval cultivation, especially mysid shrimp before larvae, which are more sensitive to it and have enhanced tolerance in the larval stage. However, during the entire nursery period, the total ammonia is required not to exceed 0.5 mg/L.

②Dissolved oxygen. The dissolved oxygen content in the nursery pond is required to be no less than 4.0 mg/L. In order to meet the respiratory needs of the larvae and the consumption of oxygen by other organisms and organic matter, constant aeration is required throughout the nursery period. The aeration volume of nauplii is smaller (weak boiling shape). Later, as the larvae develop, the aeration volume will be increased. Especially after the larvae, the phenomenon of mutual cannibalism increases, and the aeration volume should be increased to about 2.0%. Therefore, the air stones should be placed more densely, with one air stone every 50 to 70 centimeters square.

③pH.

pH is the comprehensive result of physical and chemical factors and biological activities in water, and is also one of the indicators of water quality conditions. High or low pH will have adverse effects on larval cultivation. The suitable pH range for Penaeus monodon during the nursery period is 7.6 to 8.8.

④Change the water. The methods to maintain and improve the water quality of nursery ponds are to change the water, aerate and add appropriate drugs or additives. Usually, Penaeus monodon seedlings require stable water quality in the early stage. Most of them do not change or add water in the early stage. Water change starts in the later stage of larvae. The daily water change amount is 25% to 50% during the larval stage of mysid shrimp, and 50% in the early stage of larval stage. , then gradually increase, and if necessary, change the water amount to 100% every day. Sometimes the water is changed by draining and filling at the same time to avoid excessive changes in water quality in a short period of time and a short-term increase in larval density, which may have adverse effects on the larvae. Some nurseries do not change the water before larvae, and insist on using Monocystis algae to control water color. Make the pond water in the _-shaped larval stage appear light brown, the mysid shrimp larval stage appear brown, and the larvae stage appear light brown. At the same time, control the amount of feeding and apply synergists to maintain good water quality. When the pool water in Phases P4 and 5 is increased to more than 1.5 meters, about 1/3 of the water should be changed every day. However, the density of shrimp seedlings in this method is relatively low.

(5) Light control: Avoid direct sunlight and strong light in the larvae stage of Penaeus monodon. If raised under direct sunlight, the larvae will not eat, and their bodies will become deformed, and they will die after about 2 to 3 days. up to 100%. Particularly, stages I to II are the most sensitive, and gradually increase after stage III. The light intensity is more suitable at 500 lux. Gradually increase the light intensity after mysid shrimp larvae. After the larvae arrive, the light intensity is equivalent to the brightness of a Chinese shrimp nursery, about 5000 to 8000 lux.

The content of this article comes from: "Protecting Natural Resources" by China Agricultural Press