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7.6. Fry rearing
Unit 7 - Breeding of mahseers
7.6. Fry rearing
- The swim-up fry are fed with egg yolk (a pinch for 200-300 fry) and sieved zooplankton (50 ml zooplankton for 346 fry; each ml contained 60 numbers) twice daily, morning and evening.
- This is continued for 14 days after which the fry were transferred to 25 m2 manured concrete ponds at a stocking density of 0.1 million / hectare.
- In ponds, the fry are fed ad libitum with a feed containing fishmeal (25%), ground nut oil cake (25%), ragi flour (25%) and chicken egg yolk (25%) for 53 days.
- The response of female fish to ovaprim is found to be slightly better than ovatide.
- The latent period (interval between injection and stripping) ranges between 24 and 36 hours at 20-23oC.
- The ovarian biopsy of the fish revealed oocytes at different stages of development, indicating T. khudree to be a batch spawner.
- The colour of freshly stripped eggs of varied from bright orange in farm-raised fish to pale orange in wild caught females.
- However, the developing good eggs were orange or lemon yellow in colour, while unfertilized eggs were opaque white and were periodically removed from the trays with a filler.
- The fertilization rates obtained for both the hormones were high (77-100%).
- In terms of fertilization rates, the dry method of fertilization was found to be better than the wet method at the tested milt concentrations.
- The freshly stripped spermatozoa showed a motility rate of 95-100% and duration of 1-2 minutes when activated with tap water.
- The egg and embryonic developmental stages proceed normally.
20-day-old T. khudree fry
Last modified: Thursday, 16 June 2011, 9:34 AM