GROWTH-RESPONSES OF TILAPIA-ZILLII FED DIETS CONTAINING VARIOUS LEVELS OF ASCORBIC-ACID AND COBALT CHLORIDE

Three groups of Tilapia zillii fingerlings were fed for 12 weeks on diets containing different levels of ascorbic acid (AA), cobalt chloride (CC), or untreated as control (C). Growth rates, food and protein conversion efficiencies in the different groups were compared. The best growth, food conversion ratio (FCR) and protein efficiency ratio (PER) were obtained with feed containing AA. The group fed diets containing CC showed higher growth rates and PER than those fed the control diet (P < 0.05). T. zillii fingerlings showed better performance in terms of growth rate and food conversion ratio with diets containing vitamin C than those containing cobalt chloride. The addition of formulated feeds to the fish-holding tanks did not adversely affect the water quality parameters measured - temperature, pH, dissolved oxygen, alkalinity and hardness. © 1990.