Vol. 8, Special Issue 12, Part C (2024)

This experimental study was conducted with addition of probiotic at different time intervals on the fry rearing of Rohu (Labeo rohita) to observe the growth rate, Fishes in control and 1^st month of treatment tanks were fed with commercial feed @4% body weight and @ 2% body weight of 2^nd month of treatment tanks. The experiment was made up of 4 treatments and each having 3 replicates. The Control was without biofloc, T₁ was with only once application of probiotic at the starting time of biofloc system, T₂ with daily application of probiotic, T₃ with application of probiotic in 7 days interval and T₄ with application of probiotic in 15 days interval_. The experiment was conducted for 60 days only_. Probiotic was applied as FCO (Fermented carbon organic) method. In each tank stocking density of fry was 30/150 ml with initial weight of each fry was 0.3±0.02 g. C:N ratio was 10:1 maintained with jaggery as carbon source. Various water parameters and growth parameters of fish were recorded during the experiment at 15 days interval. Highest body weight gain was 4.22±0.22 g, daily weight gain was 0.07 g in T₂. The survival of biofloc tank in T₂ and T₃ was found to be 100%. It was concluded that a biofloc system with daily probiotic addition as FCO helps in increasing the growth and immunological parameters of Rohu fry.

Highlights: The study recommended that the biofloc with daily addition of probiotic shows the highest growth of Rohu fry. This research will be helpful for the fish farmers those who are going for rearing of fry to fingerlings of Rohu as in this case the survivability is 100%, whereas normal survivability of fry to fingerling is 60 to 70%.