FT Vol.51(1)
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- ItemLength-weight Relationship and Condition Factor of an Endemic Carp, Osteobrama cunma (Day, 1888) of Manipur(Society of Fisheries Technologists (India)Cochin, 2014)In the present study, it has been observed that the highest condition factor was found at 30-40 mm length group, which is very near the length at first maturity of around 30 mm. Similar results was obtained by Masud & Singh (2011). The fluctuations in the condition factor in different length group might be associated with cyclic physiological process by showing repeated development of gonads and shedding of mature ova (spawning) respectively during the life of the fish and it has been observed in Gudusia chapra by Masud & Singh (2011). Findings of the present study will be useful in stock assessment and conservation of Osteobrama cunma.
- ItemInfluence of Aeration Timings on Growth, Survival and Production of Labeo rohita (Hamilton) Fingerlings during High Density Seed Rearing(Society of Fisheries Technologists (India)Cochin, 2014)A 60 day study was conducted to evaluate the impact of different timings of aeration during night hours between 18.00-24.00 h, 21.00-03.00 h and 24.00-06.00 h on growth, survival and production performance of rohu (Labeo rohita) fingerlings against a control with no aeration, in 50 m2 outdoor concrete tanks (10 m×5 m×1.3 m). L. rohita fry were stocked at a density of 0.5 million ha-1. Compared to control, aeration caused significant increase in survival, harvested size, specific growth rate and net biomass production while the feed conversion ratio significantly reduced. However, varied timing of the night aeration could not yield any significant difference in these yield attributes among the aerated treatments. Further, comparison of night aeration between 21.00-03.00 h and 24.00-06.00 h revealed relatively better performances of the fingerlings in the later treatment, indicating effectiveness of aerating the tanks after midnight (24.00- 06.00 h).
- ItemInduced Breeding and Larval Rearing of Snow Trout (Schizothorax niger Heckel) in Kashmir Himalaya with the Application of Ovatide(Society of Fisheries Technologists (India)Cochin, 2014)Induced breeding was carried out successfully in Schizothorax niger with the application of synthetic hormone, ovatide. This is the first report of induced breeding of snow trout from Kashmir waters through use of any hormone preparation. The male and female brooders were injected with calculated doses of ovatide at the rate of 0.5 ml kg-1 body weight of female brooders and 0.3 ml kg-1 body weight of male respectively. The brooders responded well to the hormone and spawned within the breeding pool. A fertilization rate of 85% was achieved. Hatchability rate was around 65%. The juveniles were initially fed with skimmed milk powder and emulsified hen egg yolk in the ratio of 1:1, supplemented later with live zooplankton. On rearing, the fry attained a size of 25 mm and average body weight of 130 mg during a period of 90 days with a cumulative survival rate of 60% from fertilized eggs to swim up fry.
- ItemGrowth and Survival of Penaeus monodon (Fabricius, 1798) in Monosex and Mixed-sex Cultures(Society of Fisheries Technologists (India)Cochin, 2014)Sexual dimorphism is apparent in black tiger shrimp Penaeus monodon (Fabricius, 1798) with females achieving larger size than males. An experiment was conducted to compare rearing of all female and all male P. monodon with a mixed-sex population using juveniles segregated by hand-sexing. External sex differentiation of postlarvae started after 55 – 60 days of rearing when they reached 2.5 g and 7.0 cm size. Healthy juveniles (4.46 ± 0.54 g; 8.55 ± 0.30 cm for males and 4.35 ± 0.38 g; 8.54 ± 0.20 cm for females) were stocked in 250 l circular cement tanks with water of salinity 18 ± 2 g l-1 at a density of 8 individuals per tank (equivalent to a density of 12.5 m-2). The treatments were all male, all female, and mixed-sex juveniles at a ratio of 1:1, with five replicates in each one. The animals were fed with a commercial shrimp starter feed for 50 days. All female shrimps attained significantly higher growth of 40% and 43% compared to all male and mixedsex treatments, respectively, with greater specific growth rate and protein efficiency ratio, and lower feed conversion ratio (p<0.05). Survival rates were not significantly different among treatments. The male growth in the all male and mixed sex treatments was similar, while the female growth was significantly higher in the all female treatment compared to that in the mixed sex treatment. Results of this study demonstrate the benefit of all female culture of P. monodon over the conventional mixedsex culture although more trials are recommended to establish its commercial attributes.
- ItemEffect of Marigold Oleoresin on Growth, Survival and Pigmentation in Orange Chromide, Etroplus maculatus (Bloch, 1795)(Society of Fisheries Technologists (India)Cochin, 2014)The study was conducted to evaluate the effect of marigold oleoresin on growth, survival and total carotenoid content in muscle tissue of Etroplus maculatus. Fish with size group ranging from 0.60 g to 0.62 g were used for the study. The study was carried out in triplicate groups for a period of 45 days. Fishes were stocked at the rate of 15 per tank. Three test diets namely T1, T2 and T3 with 30% protein level were formulated. Diet T1 had 60 ppm, T2 had 120 ppm and T3 had 180 ppm marigold oleoresin, and diet without marigold oleoresin supplementation served as control (T0). There was no significant effect in survival rate and feed conversion ratio of the fish (p>0.05). However, 60 ppm marigold oleoresin fed fishes showed increased weight of 1.04±0.08 g, lower feed conversion ratio of 1.53±0.05 and higher survival rate (82.14%) than the other treatment groups. The fishes fed with 60 ppm marigold oleoresin incorporated diet showed significantly higher specific growth rate of 1.36±0.21%, relative growth rate of 69.10±3.4% and the absolute growth rate of 0.42±0.02 g. The body colouration and total carotenoid concentration of muscle tissue (4.62±0.02 μg g-1) was significantly higher in fish fed with 60 ppm marigold oleoresin diet. Among the tested doses, 60 ppm marigold oleoresin showed better results than 120 ppm and 180 ppm marigold oleoresin inclusion in the fish diet.