Sharks are fish.

Sharks belong to the vertebrate phylum Chondrichthyes (Chondrichthyes) planktivorous subclass, marine, a few species into freshwater, for a group of fast-swimming medium to large marine fish.?

Shark endoskeleton is composed entirely of cartilage, often calcified, but without any real bone tissue, the exoskeleton is not very well developed or degraded, the body is often dermatodont (plasmalemma), teeth are diversified, with a hard muscle, but the membranous bone never exist, the brain cranium is seamless. The upper forehead consists of the palatine square cartilage, and the lower forehead consists of the Meissner's cartilage.

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Sharks have a diverse habit of growth. p>Growth habits of sharks

1. Growth rate. In the bait rich, temperature and other ecological factors appropriate, freshwater sharks grow faster, weight, length can be doubled, growth is mainly affected by temperature, bait, age and physiological conditions and other influences on the growth pattern is that the length of the juvenile fish to increase faster, the weight increase is relatively slow;

When the length of the body increased to a certain length, the growth rate began to slow down, while the weight is increasing rapidly. Data show that in June to October during the appropriate growth time, freshwater sharks can generally according to the average daily growth rate of more than 15 grams. Freshwater sharks kept for 2 years can grow to over 2 kilograms.

2, temperature and growth. Suitable growth water temperature of 20 ℃ ~ 33 ℃, 28 ℃ ~ 30 ℃ is most suitable. Therefore, the growing season for late April to October in the first and middle, about 20 days difference between the north and south of China.

3, bait and growth. In the case of artificial baiting, the amount and type of bait will directly affect the growth of freshwater sharks. In the species specifications, stocking density and environmental conditions are similar, whether individual growth or group production, feeding concentrate feed are better than roughage;

Concentrate feed in particular contains a certain amount of animal protein, such as fishmeal, pupa powder mixed feed grows fastest. Therefore, it is feasible to cultivate plankton through artificial fertilization to promote its growth in aquaculture.

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