How to raise fish fry

Fry culture is now a very popular culture project, but the fry is fragile and difficult to feed. Let's take a look at how to raise fish fry.

1. Feed

The newly hatched fry, which are 0.2 to 0.3 cm long, live by absorbing nutrients from the yolk sac in the body. 2-3 days after hatching, the nutrients in the yolk sac were completely absorbed, the digestive system of the fish was initially fully developed, the swim bladder was filled with gas, and the fry began to swim in all directions and look for food. For these newly fed fish fry, appropriate feeding should be made to rotifer and ciliate zooplankton, that is, "migratory water". If there is no "migratory water", you can feed the cooked egg yolk by wrapping the egg yolk with 1-2 layers of gauze and crushing it, then place the gauze bag on the water and gently pat it while moving, so that the egg yolk is evenly suspended in the water for fish to eat. Feed twice a day, and it is appropriate to finish within 1 hour. After feeding for 7 days and 10 days, the fry is getting bigger and bigger, so you can stop feeding egg yolks and feed live water fleas instead. When the fry grows to more than 1 cm, it can be fed to all kinds of rotifers.

2. Change water

After the fish fry hatch, the leftover food is stored in the water every day, and the decay over time will affect the life of the fish fry, so it is necessary to change the water. The method of dehydration should be used to change the water, that is, when changing the water, pour the fish and relatively clean old water into the new water. The first dehydration takes place about 10 days to half a month after hatching, and every other half month thereafter. After three times of dehydration of fish fry, the total length has reached about 2 cm, should be changed water. As the resistance of fish is weak, the temperature difference of changing water should be kept within 4 ℃.

3. Fish selection and pond division

In the process of the growth of fish fry, we should constantly choose the best and eliminate the bad according to the characteristics of all kinds of farmed fish, so as to ensure the cultivation of good varieties. Generally, one parent fish needs to be selected for about 4 or 5 times before it can meet the requirements. The selection criteria and methods are as follows: the first selection of fish, hatching for 10 days to half a month, the fry length of about 1.5 cm, you can start to choose, mainly eliminate single tail, abnormal tail and abnormal tail stalk. After selecting fish, the good fish left behind will be stocked in ponds at a density of about 150 fish per square meter. When the fish is selected for the second time, when the fry grows to more than 2 cm, the caudal fin has been formed. All fish without 3 or 4 fish will be eliminated. Fish selection for the third time to eliminate fish with underdeveloped dorsal fin. The good fish left behind are stocked in ponds at a density of about 120 fish per square meter. After the 4th and 5th fish selection, the fry has grown into young fish, which can be selected according to the characteristics of the species and mainly based on morphology. If the dragon eye, the size of the left and right eyeballs should be the same; the bubble of the blister eye should be large, symmetrical and so on.