Development stages of androgenic glands in Giant river prawn, Macrobrachium rosenbergii De Man, 1879 in relation to size and age, and the success rate of feminization after andrectomy in small and large size prawn

To produce all male Giant river prawn (Macrobrachium rosenbergii De Man, 1879) neofemales are produced by removing the androgenic glands of young post larvae (PL). Key to the success of sex change is having suitable PL stages which were formerly recommended according to size (carapace length, CL) or age. This study aimed at understanding the relationship between developmental stages of androgenic glands and size of M. rosenbergii and success rate of sex change after removal of androgenic glands in different size groups of PL. This is the first report on developmental stages of androgenic glands of juvenile M. rosenbergii based on histology of 30 PL/age-class (240 individuals) between 10 to 80 days after metamorphosis. The five stages of androgenic gland development are described. At a stocking density of 2500 PL/1500 l, development of androgenic glands depended on size and age. We found that the optimal PL stage for andrectomization was before development of appendix masculinae, regardless of size and age. Stocking PL at high density (e.g. 5000 PL/1500 l) extended the optimal stage for andrectomization up to PL105 compared to PL95 in the low density group. Only 84.86 ± 8.19 and 90.92 ± 17.78% (for the high and low stocking densities, respectively) of the presumed neofemales (identified by absence of appendix masculinae), developed ovaries.

Highlight
► Stages of androgenic gland (AG) development in Giant river prawn were identified.
► Development of AG depended on age and size of the postlarvae.
► Stocking PL at high density extended a period when right stage of PL was available.