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 thegrowth process. The present study aimed at evaluating the influence of varied photoperiod and stocking density on the growth andsurvival 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 and0L:24D, respectively to study the influence of varied photoperiod. T-3 and T-4 were stocked with fry at 30 and 40 m-3 densitiesrespectively to study the effect of crowding on the growth. Control at 20 m-3 density and 12L:12D photoperiod served as control forboth the studies.Result: There was a significant reduction in the survival, harvested body weight, total length and specific growth rate in the treatmentsT-1 and T-2 as compared to the control (P<0.05). Though these attributes were statistically similar (P>0.05) between T-1 and T-2, thevalues were relatively higher in T-1 suggesting considerable photoperiod effect on fish growth. Similarly, the HBW, total length and SGRsignificantly reduced from T-3 to T-4 with increased density depicting effect of crowding on growth. Such results indicated that bothincreased stocking density and decreased photoperiod lead to growth suppression and can be used as tools for seed stunting in catla.