Histological Study of Sex Differentiation in Bighead Carp (Hypophthalmichthys nobilis), Grass Carp (Ctenopharyngodon idella), Silver Carp (Hypophthalmichthys molitrix) and Catla (Catla catla)

Time of sex differentiation has been identified in four major commercial carps; bighead carp (Hypophthalmichthys nobilis), grass carp (Ctenopharyngodon idella), silver carp (Hypophthalmichthys molitrix) and catla (Catla catla). Histological differentiation of germ cells has not been previously studied in these species except grass carp. Developmental process of gonads in these species was studied from fertilized egg stage till completion of sex differentiation. Identification of this time is important to find out an appropriate time for sex reversal treatment to produce monosex culture at commercial level thus eliminating the growth rate differences between both sexes. Sex differentiation was observed at 784 degrees dph (degree days posthatch) (28 days post-hatch), 1215 degrees dph (45 days post-hatch), 786 degrees dph (28 days post-hatch) and 840 degrees dph (28 days post-hatch) in bighead carp, grass carp, silver carp and catla, respectively.