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Abstract
Impact of polyhouse culture was examined on ovarian maturity, growth, muscle and egg composition in two Indian major carps: rohu, Labeo rohitaand catla, Catla catla; and two Chinese carps: grass carp, Ctenopharyngodon idellaand silver carp, Hypophthalmichthys molitrixduring winter. Eight females (2+ years age group) of each species, were stocked in polyhouse and outdoor concrete tanks (250 m2), in duplicate. Results of the study revealed that polyhouse-cutured fishes, in general, exhibited better (P < 0.05) values for weight increment, gonadosomatic index, total number of eggs/fish, number of eggs/g body weight, and egg diameter. Proximate composition of muscle and eggs in fishes varied significantly with culture conditions. It was seen that Chinese carps attained maturity about two weeks earlier than the Indian major carps. The stage of oocyte maturation varied between fishes reared in the two culture systems. Polyhousecultured fishes possessed most oocytes (> 70%) at migrating germinal vesicle stage, while those reared in outdoor tanks exhibited these at the central germinal vesicle stage. An advancement in attainment of maturity was evident in these carps when grown in polyhouse during winter.