Influence of Photoperiod and Rearing Density of Fry in Production of Stunted Fingerlings of Catla catla (Hamilton)

Abstract

Background: Seed stunting is a process of suppressing the normal growth of fish by manipulating various factors affecting the growth process. The present study aimed at evaluating the influence of varied photoperiod and stocking density on the growth and survival of catla (Catla catla) during the stunting process. Methods: Five treatments including control were used in triplicate and stocked with catla fry (0.84 g, 38.8 mm). Control, T-1 and T-2 groups were stocked with fry at 20 m-3 densities and maintained at 12 hours light and 12 hours darkness (12L:12D), 6L:18D and 0L:24D, respectively to study the influence of varied photoperiod. T-3 and T-4 were stocked with fry at 30 and 40 m-3 densities respectively to study the effect of crowding on the growth. Control at 20 m-3 density and 12L:12D photoperiod served as control for both the studies. Result: There was a significant reduction in the survival, harvested body weight, total length and specific growth rate in the treatments T-1 and T-2 as compared to the control (P less than 0.05). Though these attributes were statistically similar (P greater than 0.05) between T-1 and T-2, the values were relatively higher in T-1 suggesting considerable photoperiod effect on fish growth. Similarly, the HBW, total length and SGR significantly reduced from T-3 to T-4 with increased density depicting effect of crowding on growth. Such results indicated that both increased stocking density and decreased photoperiod lead to growth suppression and can be used as tools for seed stunting in catla.