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The fish productivity from the reservoir in its all naturalness depends on various abiotic and biotic factors. The abiotic factors include mostly all physico-chemical parameters of water body, which have immense influence on biogenic factors and existence of flora and fauna in the reservoir. The first and foremost impact of physico-chemical parameters are experienced by the biotic community existing at the base of trophic level, which include the autotrophs like phytoplankton, which forms the very basic source of food material for the first order consumers like fishes who thrive on the pasture of phytoplankton. The physical factors like insolation, temperature, transparency had the direct impact on the existence of phytoplankton. The results obtained clearly indicates the existence of high bloom of plankton in the summer months owing to increased availability of radiant sun's energy (insolation), rise in temperature and high level of transparency accounting for the enhanced photosynthetic activity. The astonishingly high bloom phytoplankton at all the stations of the recording in the summer ensured the ample availability of food material for pelagic fishes. The length-weight measurement conducted for all the fishes from the reservoir evidently indicated the maximum gain of the growth of fishes during the summer months. The community, which derived the maximum advantage of high intensity of feeding on phytoplankton during the summer months resulting into enhanced growth, was mostly the carps (Indian major carps and minor carps) from the reservoir. The correlation of finding of fish fecundity in the reservoir to the conversion eggs into spawns at the rate of minimum 50%, it was estimated that there was addition of average number of over 20.0 Lakh from Catla catla; over 30.0 Lakh from Labeo rohita, over 20.0 Lakh of Cirrhinus mrigala, over 15.0 Lakh from Heteropneustes fossilis and Channa striatus, over 35.0 Lakh Labeo gonius. [ABSTRACT FROM AUTHOR]

Fish samples of Indian hill trout Barilius bendelisis, were collected from the Gaula river (29° 17' 25'' N Latitude, 79° 32' 143'' E) and reared in captive condition at Directorate of Coldwater Fisheries Research, Bhimtal (29°21´ N, 79034´ E, altitude 1370 m MSL).Gonadosomatic index was found maximum in May for females (13.24 ± 0.92) and males (1.13 ± 0.07) respectively indicating a single spawning period of this species under captivity. Absolute fecundity (total number of eggs) varied from 320 to 4000. The average absolute fecundity was 1661 ± 304.6 at a total length 10.07 ± 0.30 cm and body weight of 11.92 ± 1.23 g. Histological study of the ovary revealed the presence of oocytes at different stages of maturity with a maximum number of the mature oocytes during April to May. Results of the present investigation suggest that B. bendelisis belongs to a category of low fecund fish and spawns during April and May under captive condition [ABSTRACT FROM AUTHOR]

To study the reproductive biology of Horabagrus brachysoma (Günther, 1864), monthly samples were collected from the riverine stretches of Lake Vembanad during 2001-2002. The sexes can be distinguished only during the breeding season; male to female ratio in the exploited catch was 1 : 1.97. The mean L T at first maturity ( L 50) was 18.5 cm in females and 17.5 cm in males. Absolute fecundity varied between 1100 and 124 000, with a mean of 20 472. The ovary showed group synchronous development and the oocyte diameter varied between 0.13 and 1.63 mm. The relatively high fecundity and hardy nature of H. brachysoma may favour the expansion of this indigenous catfish throughout the culture systems. [ABSTRACT FROM AUTHOR]

To assess strain related differences in growth performance and growth patterns under the same culture environment, four strains of common carp, two each of the scale carp, Cyprinus carpio var. communis (Chinese big-belly carp and long bodied carp) and mirror carp, C. carpio var. specularis (scattered carp and linear carp) were communally stocked in three fertilized earthen ponds of 0.14 ha each at 5,000 fish ha−1 in the ratio of 1:1:1:1 during an 11-month (February to December) culture cycle. Chinese big-belly carp grew larger than other groups, among which there were no significant differences. Scale carp strains performed relatively better than mirror carp at higher temperatures and then essentially stopped growing as temperatures declined into winter. The strains of mirror carp, on the other hand continued growing well later into the cold season. [ABSTRACT FROM PUBLISHER]

Background. The spotted snakehead, Channa punctatus is a highly priced freshwater food fish species in India. The culture of snakeheads is still not common due to the scarcity of quality seed supply and lack of knowledge on their feeding and breeding techniques. Therefore an experiment was conducted to test the efficacy of a new spawning agent, Ovatide in stimulating ovulation of snakehead fish under a controlled captive condition. Materials and Methods. In total, 12 matured females and 24 male fish weighing 50-90 g were randomly selected for three hormonal treatment groups and one control group. Both male and female fish in each treatment group were administered with either saline (0.9% NaCl, control group), or 0.2, 0.4, and 0.6 mL of Ovatide per kg of body weight (BW), respectively. Each breeding set consisted of two males and one female. The hormone-treated fish were then held in concrete tanks for spawning. The breeding performance was evaluated based on spawning fecundity, spawning response, percentage fertilization, and percentage hatching. Results. No spawning behaviour or performance was observed in control group. Partial spawning was observed with the Ovatide dose of 0.2 mL · kg-1 BW, and complete spawning was noticed in the medium Ovatide dose (0.4 mL · kg-1 BW), and the higher dose (0.6 mL · kg-1 BW) administered fish. The highest total spawning fecundity (P < 0.05) was recorded when the females were injected with 0.4 mL of Ovatide · kg-1 BW than those injected with other doses. The latency period and the number of spawned eggs were ranged from 25 to 31 h and from 1080 to 5814, respectively. The highest fertilization- (90.6%) and hatching (91.33%) rates were also observed at the medium dose (P < 0.05). With regard to hatching rates, no significant difference was noticed between the medium- and higher doses of Ovatide-treated groups. Conclusions. The synthetic gonadotropin-releasing hormone with a dopamine antagonist at the dose of 0.4mL · kg-1 BW could be used as an appropriate stimulating agent for successful spawning and induced breeding of C. punctatus under captive conditions. [ABSTRACT FROM AUTHOR]