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International Journal of Pure & Applied Bioscience (IJPAB)
Year : 2016, Volume : 4, Issue : 6
First page : (123) Last page : (135)
Article doi: http://dx.doi.org/10.18782/2320-7051.2419

Endogenous Feeding Period of Rainbow Trout, Oncorhynchus mykiss (Walbaum), in the Raceways of Kathmandu, Nepal

Rakesh Prasad Bhagat1,2* and Sudip Barat2
1Department of Zoology, Tri-Chandra Multiple Campus, Tribhuvan University, Kathmandu-44600, Nepal
2Aquaculture and Limnology Research Unit, Department of Zoology, University of North Bengal, Siliguri-734 013, District Darjeeling, West Bengal, India
*Corresponding Author E-mail: rakesh.bhagat2009@gmail.com
Received: 4.12.2016  |  Revised: 16.12.2016   |  Accepted: 18.12.2016  

Endogenous feeding period of 2 years and 10 months old 2.0+ broods (second spawners) of rainbow trout, Oncorhynchus mykiss (Walbaum), was recorded in the farmers’ raceways. Twelve female (39.56 ± 0.25 cm and 697 ±11.15 g) and six males (39.12 ± 0.41 cm and 690.5 ± 26.46 g) were bred obtaining 1404g eggs and 309 ml milts respectively. Eggs were yellow and milt cream-coloured. Each egg was 0.405 ± 0.0091cm in diameter and 0.6025 ± 0.001g in weight and each millimetre of milts comprised 20 millions spermatozoa. Fertilization was done by dry stripping method obtaining 1299.2 g (21562 numbers) zygotes thus, ensuring fertilization percentage to be 92.56 ± 0.45%. Conversion and change of the yolk of zygotes into sac-fries for development, growth, and formation of yolk-sac and further, yolk of the yolk-sac of sac-fries into free swimming fries for development and growth were comparatively less due to small-sized zygotes because of less age and small size of the broods. The incubation period was 29 days in water temperature of 9.34 ± 0.17°C day-1 and cumulative water temperature (sum total of water temperature of 29 days) of 269.8°C with hatching of sac-fries (survivability 44.03 ± 2.42%), each 1.73 ± 0.01 cm and 0.0434 ± 0.002 g with 0.0163 ±0.001 g yolk-sac. The endogenous feeding period was 7 days in water temperature of 8.6°C liberating free swimming fries (survivability 78.26 ± 2.35%), each 1.92 ± 0.1 cm and 0.0406 ± 0.002 g. Total incubation period was 36 days in water temperature of 8.6-11.2°C. 

Key words: Zygotes, Conversion and change, Sac-fries, Endogenous feeding period, Free swimming fries.

Full Text : PDF; Journal doi : http://dx.doi.org/10.18782

Cite this article: Bhagat, R.P. and Barat, S., Endogenous Feeding Period of Rainbow Trout, Oncorhynchus mykiss (Walbaum), in the Raceways of Kathmandu, Nepal, Int. J. Pure App. Biosci.4(6): 123-135 (2016). doi: http://dx.doi.org/10.18782/2320-7051.2419