The quality of good fingerlings is passed, and the scientific breeding benefits are good
_Guo Zhiwen
First, the specification of the form
Homogeneous fingerlings are uniform in size, strong in physique, high in the back and thick in flesh, which is a high-quality fish fingerling. On the contrary, such as thin physique, dryness, small individuals, large head, thin tail, body in the shape of knife back, poor physique, low survival rate is inferior fish species.
Second, the color of the body surface
The quality of fish species is clearly reflected in body color, high-quality fish species have distinct colors, and the body color of different types of high-quality fish species is different: the body color of bluefish is grayish white, the more robust, the lighter the body color; the grass carp body color is pale golden yellow, the gray-black reticulated scales are obvious, the more robust, the more pronounced the golden body color; the silver gray of the silvery back, the silver white of the abdomen, the more robust, the more bright the silver white; the body color of the bighead carp is golden brown, the black spots on both sides, the stronger, the lighter the black, the more pronounced the golden yellow. All fingerlings that are black, gray and dull in body color are unhealthy and inferior fish species. Fish fingerlings are high-quality and robust, and there is a layer of mucus on the surface of the body to protect the scales and skin from germs, while the sick and weak fish lack mucus, and some sick fish have more mucus on the surface of the body, and the body surface is dull, commonly known as the "hair" of the fish body, such as the fish species are dark or dark black, which is a skinny fish or a sick fish.
Third, the ability to move
Robust fish species swim lively, strong against the water, in the cage or live water intensive stocking of fish fingerlings head down, only can see the tail swinging, the fish species into the basin and other containers, tail fin twisting and bouncing force is strong, high-quality fingerling gill cover tightly closed. When the fingerlings are just fished out of the car compartment, the beating is agile and powerful, indicating that the fish species have a good physique; when fishing out, the fish fingerlings are soft, weak and do not beat, indicating that the fish species have a poor physique. There are two main factors that lead to the weakness and weakness of fish species: First, they stop eating too early, and the fish species have a weak physique, which has a large head, a thin trunk and no flesh, and a slender tail handle. The second is hypoxic coma or carbon dioxide poisoning coma, hypoxic coma mostly occurs in short-distance transportation, insufficient oxygen supply, this fish in the hypoxic coma time is short, put into the pond, soon can return to normal state; coma time is long, will cause a large number of deaths. Carbon dioxide poisoning coma mostly occurs in long-distance sealed warehouse transportation, when the concentration of carbon dioxide in the water body is too high, it will enter the blood of the fish body in large quantities, resulting in a decrease in blood pH, decreased hemoglobin oxygen carrying capacity, and when severe, it will lead to fish coma or death. Fish with carbon dioxide poisoning, when in a mild coma, after being put into a large body of water, it takes several minutes to return to a normal state; in a deep coma, it is generally difficult or completely impossible to recover.
Fourth, the body surface characteristics
The body surface of the fish species is plump, no deformity, no crooked body, the scales are complete, the fins are not damaged, the length of the fish body is proportional to the weight, the high-quality fish species are large, the survival rate is high, and the growth rate is fast. The fish body is smooth and round, indicating that the skin of the fish species is normal; if the skin of the fish body is rough and prickly, it means that the surface mucus of the fish body is less or disappears, losing the protection of mucus, the fish body is more likely to be injured, susceptible to infection by pathogens, losing the barrier of mucus, and the external moisture will penetrate into the fish body through the skin in large quantities, so that the osmotic pressure in the body is unbalanced, and the survival rate is greatly reduced.
5. Disease situation
High-quality fingerlings are disease-free. In winter, some pathogens completely die and disappear, and some lurk in fish bodies, and are brought in and spread by fish species, such as anchorhead loach, ringworm, wheelworm, gill cryptoflagellus, myxosporidium and so on. The anchorhead gills that parasitize the surface of the fish body are visible to the naked eye; the finger worms, wheel worms, and hidden whipworms that parasitize the gills can be detected with the help of microscopes; parasites or bacteria parasitizing the intestine must be dissected to confirm the diagnosis. There are also some pathogens, such as myxosporidium, bacteria, viruses, etc., which must investigate the origin of fish fingerlings, and strictly prohibit the entry of fish species in epidemic areas. Before stocking all fingerlings, the appropriate drugs must be selected for prevention based on the test results.