Crab seedlings, commonly known as “major larvae,†are the fifth stage of the larvae that have been peeled and become large larvae. It has a pair of compound eyes attached to the long end of the eye socket, which is named after the eye socket. Large-eyed larvae are the basis for breeding crabs and breeding crabs. The quality of these large-eyed larvae directly affects the survival rate of young crabs from phase II to V. Therefore, attention must be paid to the purchase of crabs.
First, understand the cultivation process of crab seedlings
Before purchasing crab seedlings, farmers should first understand the entire production process of the crab seedling farm, including: pro-crab size, feed use, breeding cycle, and so on. The pro-crabs used to propagate crab seedlings are best sourced from natural lakes and large bodies of water. The female and male crabs should come from different water areas to avoid inbreeding. Pro-crab size: Female crabs should not be less than 125 grams each, and male crabs should not be less than 150 grams each.
The crabs cultivated using Artemia larvae have better quality, and the quality of crabs cultivated with substitute feeds such as freshwater quail and egg yolks is poor.
In addition, the crab breeding cycle is generally 19 days to 21 days, and the water temperature at the time of emergence is about 21°C.
Second, do a good job of crab quality identification work
1. The body of the high-quality crab is light yellow, shiny and transparent. There are no foreign objects such as poly-dentin or filamentous bacteria on the body surface of the microscope. Inferior crab seedlings, dark body color, deep and shallow, milky white, orange, microscopic examination of crab seedlings, with insects.
2. High-quality crab seedlings are robust, uniform in size, have phototaxis, and are fierce in feeding and strong in retrogression. Feelings of crawling crabs are powerful and quick to respond with mouth blowing. Grab a small amount of crab seedlings by hand, shake the water and gently hold it into a mass, and immediately spread it after loosening it. Inferior crabs, empty stomach without food, poor swimming ability, easy to move in the bottom of the water, hand crabs easy to become a group, not easy to spread.
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