How to raise fish fry? Master these key breeding techniques

Raising fish fry is a very popular breeding project nowadays, but fish fry are fragile and not easy to keep alive. Below let's take a look at how to raise fish fry.

1. Feeding bait

Newly hatched fish fry, with a body length of 0.2-0.3 cm, live by absorbing nutrients from the yolk sac inside their bodies. 2-3 days after hatching, the nutrients in the yolk sac are almost completely absorbed, the fish's digestive system has initially developed fully, the swim bladder is filled with gas, and the fish fry begin to swim in all directions and look for food. For these fish fry that have just started feeding, rotifers and ciliate-type zooplankton, namely “infusoria”, should be fed in appropriate amounts. If there is no “infusoria”, cooked egg yolk can be fed; the method is to wrap the egg yolk with 1-2 layers of gauze, squeeze it into pieces, then place the gauze packet on the water surface and pat it lightly, moving while patting, so that the egg yolk is evenly suspended in the water for the fish to eat. Feed 2 times a day, and the feeding amount should be eaten within 1 hour. After feeding this way for 7-10 days, the fish fry gradually grow larger, and feeding egg yolk can be stopped and live water fleas can be fed instead. When the fish fry grow to more than 1 cm, various types of rotifers can be fed.

2. Changing water

After the fish fry hatch, leftover food accumulates in the water each day, and if it spoils over time it will affect the lives of the fish fry, so the water needs to be changed. Water changes should use the dehydration method, that is, when changing the water, pour the fish together with the relatively clear old water into new water. The 1st dehydration is carried out about 10 days to half a month after hatching, and thereafter once every half month. After 3 dehydrations, the fish fry have reached a total length of about 2 cm, and a water change should be carried out. Because the fish's resistance is relatively weak, the temperature difference for water changes should preferably be kept within 4°C.

3. Selecting fish and dividing into ponds

During the growth process of the fish fry, according to the characteristics of various cultured fish, the superior should be continuously selected and the inferior removed, so as to ensure the cultivation of excellent varieties. Generally, 1 brood fish kept for breeding needs to go through about 4-5 selections before it can meet the requirements. The selection standards and methods are as follows: In the 1st selection, 10 days to half a month after hatching, when the fish fry have a body length of about 1.5 cm, selection can begin, mainly eliminating those with a single tail, deformed tail, or an improper caudal peduncle. After selection, the good fish left behind are divided into ponds for stocking at a density of about 150 fish per sq m. In the 2nd selection, when the fish fry grow to more than 2 cm, the caudal fin has already formed. All fish that do not have 3 tails or 4 tails are eliminated. In the 3rd selection, fish with incompletely developed dorsal fins are eliminated. The good fish left behind are divided into ponds for stocking at a density of about 120 fish per sq m. In the 4th and 5th selections, the fish fry have already grown into young fish, and selection can be carried out mainly based on morphology in combination with variety characteristics. For example, in dragon-eye goldfish, the left and right eyeballs should be the same size; in bubble-eye goldfish, the bubbles should preferably be large and symmetrical on the left and right, and so on.