Methods for identifying the quality of fish species
The quality of fish species has a great impact on fishery production, and the advantages and disadvantages of fish species can be identified from the following aspects.
First, the specification of the form
The same type of fish species 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, the physique is thin and weak, dry, the individual is small, the head and tail are thin, the body is knife-back-shaped, the physique is poor, and the survival rate is low, which is inferior fish species.
Second, the color of the body surface
The quality of fish fingerlings is clearly reflected in the body color, the color of high-quality fish species is distinct, and the body color of different species of high-quality fish species has different methods for identifying the advantages and disadvantages of fish species. The body color of the bluefish is grayish white, the more robust the fish species, the lighter the body color; the grass carp body color is light golden yellow, the gray-black reticulated scales are obvious, the more robust the fish species, the more pronounced the golden body color; the silver gray of the silvery back of the white carp, the silver white of the abdomen, the more robust the fish species, the more brilliant the silver white; the body color of the bighead carp is golden brown, there are black spots on both sides, the more robust the fish species, the lighter the black, the more prominent the golden yellow. All fingerlings that are black, gray and dull in body color are unhealthy and inferior fish species. If the fish species are high-quality and robust, they have a layer of mucus on the surface of the body to protect the scales and skin from germs, while the sick and weak fish species lack mucus. There are also some diseased fish with more mucus on the surface and dull on the surface, commonly known as the "hair" of the fish body. If the body of the fish species is dark or dark black, it is a thin fish or a diseased fish.
Third, the ability to move
Robust fish species swim lively, strong against the water, in the cage or live water intensive hoarding of fish fingerlings head down, only the tail can be seen swinging, the fish species into the basin and other containers, robust fish species tail fin twisting and bouncing force is strong. The gill caps of high-quality fingerlings are tightly closed. When the fingerlings are just fished out of the trunk, the beating is agile and powerful, indicating that the fish species have a good physique; if they are fished out, the fingerlings are weak and do not jump, 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, premature stopping of eating, thin physique of fish species, this fish head is large, the trunk is thin and fleshless, and the tail handle is slender. The second is coma caused by hypoxic coma or carbon dioxide poisoning. Hypoxic coma often occurs during short-distance transport, and coma is due to insufficient oxygen supply. This fish can quickly return to normal after being placed in a large pond when in a short period of hypoxia coma; if the coma is too long, it will cause a large number of fish species to die. Carbon dioxide poisoning coma mostly occurs in long-distance sealed box 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 the blood pH of the fish species, a decrease in the oxygen carrying capacity of hemoglobin, and when it is serious, it will lead to fish coma or even 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 to recover or even completely unable to recover.
Fourth, the body surface characteristics
The normal body surface characteristics of fish species are full body surface, no deformity, no crooked body, complete scales, undamaged fins, and the length of the fish body is proportional to the weight. High-quality fingerlings have large sizes, high survival rates, fast growth, smooth and rounded fish bodies, and normal skin. If the skin of the fish body is rough and prickly, it means that the mucus on the surface of the fish species is less or disappears. Once the mucus protection is lost, the fish body is more likely to be injured and susceptible to infection by pathogens; without the mucus barrier, the external moisture will penetrate into the fish body through the skin of the fish, so that the osmotic pressure in the fish body is unbalanced, and the survival rate of fish species is greatly reduced.
5. Disease control
In winter, some pathogens completely die and disappear, and some lurk in the fish body and are brought in and spread by the fingerlings, 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 ringworms, wheelworms, and hidden whipworms that parasitize the gills on the gills can be detected with the help of microscopes; parasites or bacteria parasitizing the intestines must be dissected. There are also some pathogens, such as myxosporidium, bacteria, viruses, etc., which must investigate the origin of fish fingerlings, and it is strictly forbidden to introduce fish species from endemic areas. Before stocking all fingerlings, the appropriate drugs must be selected for prevention based on the test results.