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Habitat Crayfish has strict requirements on the water environment. It can survive in water bodies with a pH of 5.8 to 8.2, a temperature of -15°C to 40°C, and a dissolved oxygen level of at least 1.5 mg/L, in most parts of China. Can naturally winter. The optimum pH for the growth of the crayfish is 7.5 to 8.2, the dissolved oxygen is 3 mg/l, and the water temperature is 20 to 30°C.
The crayfish is sensitive to temperature, and there is a clear phenomenon of day and night vertical movement. When the light is strong, it sinks into the water or hides in the cave. When the light is weak or dark, it starts to move. Usually, it clings to the water grass or suspended matter in the water and lays on the side of the body. On the surface of the water, and with the habit of digging holes, the depth of the excavated cave is between 50 and 80 centimeters.
Dietary crayfish are omnivorous animals, all kinds of fresh aquatic plants, benthic animals in the water body, mollusks, large zooplankton, fish and shrimp corpses and similar bodies are their favorite food, artificial feeding feed is also very like eating. The larvae began to ingest phytoplankton and small larval larvae, rotifers, etc. after the first oyster shell. Crayfish are more gluttony, when the food is not enough, they will be similar to the rest of the group, to eat small, just the shell or just shell clams of soft-shelled shrimp is most likely to be eaten.
Breeding habits Crayfish spawn several times a year, in the natural environment of sexual maturity of 9 to 12 months, has reached sexual maturity of a general weight of 30 to 100 grams. The mating season is generally from late April to July. The peak of mating in May is in May. It can spawn 3 to 4 times a year, spawning 300 to 800 capsules each time. Before mating, females first undergo genital molting and the molting process takes about 2 minutes. During mating, the females lie on the surface of the water. The males chelate their claws before clamping the females, and then they hold the females and insert the transfer device into the females. The mating time is 10-30 minutes. After 3 to 10 hours of mating, the females begin to lay eggs and the fertilized eggs adhere to the abdominal limbs for development. The length of embryo development is closely related to the water temperature. The higher the water temperature, the shorter the incubation time, and the lower the water temperature, the longer the incubation time. The larvae usually hatch after 5-8 weeks.
Shells and crayfish grow through the oyster shell to achieve body weight and body growth. After shelling, the new shell hardens after 12 to 24 hours. Shell is closely related to water temperature, nutrition and individual development. The larvae are usually molted once every 4 to 6 days. If the water temperature is high and the food is sufficient, the time between skins is short. Under the conditions of suitable water temperature and sufficient feed, the shrimp seedlings can grow for 3 to 4 months, and the body length can reach 8-12 cm, the weight can be 15-20 grams, and the maximum can reach 30 grams or more. (Lijiang Fishery Bureau Liu Furong Li Zhen)
Crayfish Culture (II) Dietary Feeding
Morphological characteristics Crayfish body type thick, thick crust, dark red. The body surface is covered with a layer of sharp chitin shell, the body consists of 21 sections of the head and chest and abdomen, the head and chest are slightly larger, the head has 3 pairs of tentacles, the tentacles are near the head and the tip is small and pointed. There are 5 pairs of steps on the chest, 1 to 3 pairs of feet at the end of the step, and 4 to 5 pairs of feet at the end of the step. The second step is particularly well-developed and becomes a great chelator, and male chelators are more developed than females. There are five powerful tail fans in the tail of the crayfish. The female squid bends inwards during the egg-holding period and hatching period. When crawling or being attacked by predators, it protects the fertilized eggs or young shrimps from injury.