Grouper Seed Breeding Techniques
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Second, the bait series larvae began to feed on the 4th day after hatching, but the yolk sac has not disappeared and is in a mixed nutrition stage where endogenous nutrition and exogenous nutrition coexist. After the disappearance of the yolk sac, there is a dangerous period of larvae. If you do not provide enough palatability food in time, larvae will die. There are three bait conversion stages during the development of gambral larvae to juveniles of blue groupers: yolk sac larvae to late larvae, from endogenous nutrition to exogenous nutrients; late larvae to juveniles, feeding The conversion period from small zooplankton to macrozooplankton; in the late juvenile and juvenile period, the conversion period is based on benthic diets. The corresponding series of bait is: Oyster fertilized eggs and larvae - rotifers - Artemia larvae - copepods, Artemia adults - shrimp and fish, shrimp, shellfish meal. Due to the difficulty of large-scale supply of oyster eggs and tunicate larvae, the scale of grouper fry cultivation has been limited. S- and SS-type subminiature rotifers have been used to replace the oyster eggs as the initial feed for grouper fry. Several hours before the opening of the larvae, 10 s. During the 4th to 8th day after larvae grouper hatched, the rotifer's food intake increased with the increase of light intensity after sunrise. However, the peak food intake occurred at 13:00 to 15:00, and the light intensity was 1200 lx to 2100 lx. The average daily satiation at this stage was 19.6 to 44.2 rotifers, and the daily average food intake was 109.6 to 247.8 rotifers. Feed 1 million larvae, from the opening to the 8th day of age, supply at least 1,108-25,108 rotifers per day. During the above-mentioned feeding of zooplankton, the “green water†technique should be used to add monomonas in the water, and the density should be maintained at 10104 to 25104 cells/ml in order to strengthen cultivation, improve water quality and ecological environment of the water body.
Third, the daily management of the early cultivation of the first 7 days to 10 days is best to use static water micro-inflating cultivation. Add “green waterâ€, the amount should not be too large, otherwise it will lead to bubble fish disease larvae due to excessive algal breeding. During the period of hydrostatic cultivation, change the water regularly every day, change the amount of water to 1/4 of the seedling incubator, and gradually increase it to 1/2. Usually pay attention to the bottom, daily timing. Livestock larvae over 7 mm in length can cause mutual food gluten, which greatly reduces the survival rate of seedlings. In order to avoid the phenomenon of mutual grueling, a series of cultivation measures should be taken. The first is to divide the pool by larva size, and to sort it once every 5 days to 7 days; second is to increase the frequency of feeding, 4 times to 5 times daily feeding; the third is to cultivate the density properly. About 10 millimeters long larvae rearing density is less than 10000 / cubic meters, larvae over a full length of 10 mm when the cultivation density is 500 / cubic meters to 1000 / cubic meters; fourth is to set shelters in the water, such as the bottom of the plastic Tubes, etc., can reduce mutual food. In addition, in the cultivation and management of grouper seedlings should also be based on their early life history, distribution of water layer, growth and food and other characteristics of reasonable arrangements and proper handling. When the juvenile period is turned into benthic life, the phenomenon of over-concentration of the population sometimes occurs, and it is necessary to maintain the flow of water and regulate the water temperature so as to prevent the occurrence of the above phenomenon.