Finfish Breeding and Hatchery Management

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 20-23^oC.
• 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