Influence of maternal weight, age, larval feeding and their interactions on the hatchery outcomes of an Indian major carp (Labeo rohita, Hamilton 1822)

Abstract

Broodstocks’ size (weight or length), age and larval feeding are crucial in the production of good quality gametes and larvae in any fish. Therefore, this study was conducted with two experiments to understand 1) effects of maternal weight and age, and 2) effects of maternal weight, age, larval feeding and their interactions on egg and larval traits using the Indian major carp (Labeo rohita). In both experiments, females were divided into two size groups based on their body weights (‘large’ and ‘small’) to obtain eggs and larvae. In experiment-1, parameters of egg quality such as egg weight, egg number, egg diameter, egg area and hatching rate were assessed, and larvae were reared up to two weeks with optimum feeds to evaluate their traits such as deformation rate, survival rate, total length and body area. In experiment-2, only the three-day old larvae were randomly assigned into two feeding regimes (‘everyday’ and ‘every other day’) up to two weeks to assess their fitness. The results revealed that egg weight, hatching rate, larval total length, body area increased significantly (P <0.05) and hatchling deformation rate decreased significantly (P <0.05) with the increase of female age, whereas only egg weight was linearly related to female weight (R2 = 0.47, P <0.05) in experiment-1. The experiment-2 showed that everyday fed larvae had significantly (P <0.05) higher survival rate, total length and body area than those fed every other day. The dietary treatment found no significant effects of maternal age, weight and their interactions with larval feeding. Thus, the study showed that maternal body weight, age and larval feeding may influence some traits of egg and larval fitness. The overall findings suggest that maternal weight, age and regular larval feeding must be considered to produce good quality of gametes and larvae for sustainable production of this species.