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Freshwater prawns

Natural habitat of the giant freshwater prawns covers all the countries of South-East Asia from India to China, as well as the islands of Oceania and North Australia. The main habitats - and lower reaches of the river estuaries. For spawning (spawn) shrimp dipped in freshened the mouth of the marine areas, and larval development of its happening in brackish water. Optimal for breeding, nutrition and growth of the giant freshwater prawns is water with a temperature of 28-30 degrees C, at 20 degrees C, it ceases to eat, and below 13 C begins her death.

During its development the larvae are 12 stages, each of which lasts about three days and ends линькой. After the last larval stage is molto metamorphosis in larva, which also often fade and grow quickly. With age, the frequency of sheds is reduced.

Molto - a critical period in the life of shrimp, accounting for the maximum of their death. At this time shrimp become sensitive to all unfavorable abiotic factors and more accessible to cannibalism and predators.

In our experiments, when the content in the ponds of the shrimp reach sexual maturity at the age of 4-5 months, females with a length of 72 - 105 mm and a weight of 4 - 10 g, and males respectively 89 - 95 mm and mass of 10 to 12 g. After puberty because of the large energy costs associated with the produces caviar, the growth of females somewhat slows down. In contrast to females, males have a higher growth rate and after puberty.

With nine months of age giant freshwater prawn and can reach a weight of 100 - 120 g, to a year - 140 - 150 g, and sometimes 200 g the Maximum size of the females - 200 g, the length of 283 mm, the males, respectively, 250 g and 326 mm. At the same time, the weight and size of the shrimp even in the same litter is a very big difference.

A characteristic feature of the behavior of the giant freshwater prawns is that it during cultivation in ponds never buried in the ground, not making holes, but hiding in various kinds of natural and artificial shelters. So in ponds or pools, where they are kept, it is necessary to create artificial shelter from the remnants of delhi (especially brown), tiles, tile, sheets of slate, fragments of pipes, special "book-shelves".

For shrimps this species is characterized by night activity. During the day she, as a rule, is hiding in shelters and so little is available for fish-eating birds, predatory fish, less exposed to cannibalism.

East river shrimp, which was also brought in to the water bodies of the Astrakhan region in Russia, in contrast to the giant freshwater prawns, more likes the cold, winter brings in natural waters, breed in fresh water, but is slow rate of growth and the smaller sizes; reaches a length of 130 - 150 mm and a maximum weight of 11 - 17 h. The natural area of the shrimp catches more northern areas of China, Japan, Vietnam. On the biology and behaviour close to the giant freshwater shrimp.

The first appearance of the east river prawns in the USSR were observed in 50 - 60-ies in the water reservoirs - coolers many GRES, as well as in natural reservoirs of Central Asia and some areas of Kazakhstan with the delivery of the larvae of herbivorous fish from Vietnam.

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