Reproductive biology of cultured common carp in Uzbekistan was studied. The ages, total lengths of the samples studied ranged 1-5 years, 5.0 - 87.0 cm in standard length. In spring, 1-year-old fish (8.0-25.0) cm had gonads at stage I; 2-years-old females (18.0 – 33.0 cm) had gonads at stage I (23 %) and II (77 %); 3-years-old females (25.6–47.1 cm) had ovaries at stage II (43 %) and III-IV (57 %); all 4-year-old and 5-year-old females were mature. Females mature when they reached 32 cm in standard length. Absolute fecundity varied 131–1830 thousand eggs, relative fecundity was 190.5–344.0 eggs/g of gutted fish body, real fecundity was 200.0–1300.0 thousand eggs. Average individual ripe egg size varied 1.32–1.52 mm. Positive correlation between maturation, absolute fecundity and growth was determined. For broodstock forming optimization, additional (to body size) fish characteristic should be entered to selection; fish growth could be recommended as such measure. Annual artificial selection of fishes with standard length at different ages (at least SL1 – 13 cm; SL2 - 25 cm; SL3 – 32 cm) would form broodstock which mature at 3-years-old age with real fecundity 800 – 1300 thousand eggs.
The study was carried out in 2014-2018 at the Tudakul reservoir, Uzbekistan. Samples included 278 European bream (Abramis brama), and 83 Amur white bream (Parabramis pekinensis). The age, total length and weight of the fish varied from 1 to 5 years, from 14 to 50 cm, from 30 to 1,405 g for the European bream and from 1 to 6 years, from 24 to 53.5 cm and 105 – 2,138 g for the white Amur bream and European bream, respectively. The relationship between total length (TL) and weight (W) is described by the equation W = 0.005 * TL3.2555 (r = 0.98) for European bream and W = 0.005 * TL3.201 (r = 0.96) for white Amur bream. Recovered average growth rate of European bream: TL1 - 13.5 cm; TL2 - 28.1 cm, TL3 - 37.95 cm, TL4 - 42.6 cm, TL5 - 48.6 cm.The average height of the Amur white bream: TL1 - 12.6 cm, TL2 - 23.3 cm, TL3 - 31.5 cm, TL4 - 37.9 cm, TL5 - 41.7 cm, TL6 - 44.2 cm. Lee’s phenomenon did not appear. All yearling fish were juvenile. In 2-year-old fish of both sexes of both species, the gonads were at stage II. Males and females of both species reached their first maturity at 3-4 years of age, when the total body length of the European bream was 30–32 cm, and the Amur white bream was 34–35 cm.
The goal of present study was to examine gibel carp, Carassius gibelio (Bloch, 1782) growth, maturation, fecundity and ripe eggs size under pond fish culture conditions and conditions of natural water bodies of the River Syrdarya, Uzbekistan. Gibel carp originally came from the River Amur (Russia), it was introduced to Uzbekistan in 1950s. Recently, it is wide spread species in local ichthyofauna. Females matured for the first time at age 2 years: in ponds in 8-10 cm in standard length, in the river in 18-20 cm. The GSI increased to spawning up to 2.9 – 25%. In fish farm ponds absolute fecundity was 1,4 – 51,300 eggs, in the River Syrdarya - 9,2 – 91,400 eggs. Relative fecundity in all populations was 21 – 590 eggs/g in weight of gutted fish. In April, there were two peaks of ripe and yolk eggs size: 1st - 0.89 – 1.69 mm, 2nd – 0.69-0.9 mm.
In May-June 2019, the development of organisms of the natural food base in fry ponds was studied during the rearing of cultured cyprinids in the brackish water of the drainage system and when using a new type of fertilization/feeding of larvae - soy milk. In the samples, 76 species, forms and varieties of microalgae were noted. The total number of phytoplankton microalgae was 108,512.5 x 103 cl/l, biomass -20.5776 mg/ml. 10 species were found in the zooplankton of ponds (rotifers, cladocerans, copepods); the number of zooplanktoners varied 20.5 - 266.5 thousand ind./m3, biomass - 0.14 - 406.3 g/m3. 12 species of organisms have been recorded in the benthofauna. From a technological point of view, the results of rearing with the use of soy milk turned out to be very high: in 1 month of rearing juveniles of cyprinids in monoculture, fry of 4.5 - 9 g in size were grown from prelarvae with a yield of 43 - 49%.
This article provides information on the growth of pike perch (Sander lucioperca) of Lake Tuzkon, which is part of the Aydar-Arnasay system of lakes. As a result of the research carried out, the age composition of the catches was determined: at the age of 1+ - 16.5%; 2+ - 38.5%; 3+ - 17.5%; 4+ - 12%; 5+ - 7.6% and 6+ - 8.0%. It was determined that pike perch in the first year of life grows to an average of 26.40 cm, in the second year - up to 44.45 cm, in the third - up to 53.35 cm, in the fourth - up to 67.37 cm, in the fifth and sixth years, respectively - up to 70.39 and 76.20 cm.
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