EFFECT OF DIFFERENT PHOTOPERIODS ON GROWTH, FEED UTILIZATION AND SURVIVAL OF HETEROCLARIAS HYBRID

摘要

One hundred and twenty fmgerlings of Heteroclarias hybrid with initial mean weight of 6.2g were reared in concrete tanks using three different photoperiods to investigate the effect of light on their growth performance and survival. Three photoperiodstagged: Tank A (24L: 00D), Tank B (12L: 12D) and Tank C (00L: 24D) were used in the study. Fish were fed twice daily for a period of six weeks. The result obtained showed significant increases in body weight, relative growth rate (RGR), specific growthrate (SGR) and gross food conversion efficiency (GFCE) among fishes under 24 hours darkness (Tank C). Prolong light hours was observed to stress the fish and caused reduced growth. Survival rate was also observed to be 100% in Tank C. The high growth increase recorded in Tank C was attributed to suppression of swimming activity, aggression and stress in the dark and therefore more energy was converted to body weight. The study recommends the rearing of Heteroclarias fmgerlings in conditions of continuous darkness or low light intensity for optimal growth pcrfonnance, feed utilization and survival.