A Perspective on the Ingestion and Nutritional Effects of Feed Additives in Farmed Fish Species

The use of feed additives as natural growth promoters has received considerable attention in the aquaculture industry. Besides, the utilization of antibiotics, antioxidants, feed stimulants, feed colourants as well as the use of hormones has been well established by several authors. However, the absorption or ingestion rate of the widely used feed additives by cultured fish species has not been thoroughly quantified and researched in fish nutrition while on the other hand; further investigation needs to be focused on the nutritional effects of the commonly used feed additives in the aquaculture industry. In spite of the growing interest and success obtained using feed additives as supplements in farmed fish diets, several physical anomalies or alterations in the normal development of farmed fish species have been reported by several authors. The present review therefore emphasizes on new areas of further research to improve growth, feed utilization, absorption or ingestion rates and disease resistance in cultured fish species fed feed additives. Special emphasis is focused on the elucidation of the biochemical contents and dietary supplementation levels of feed additives by cultured fish species which has received relatively little attention in the aquaculture industry. The development of a cost-effective new natural source of antioxidant; the development of algal meal-based diets as feed additives; adoption of a reliable and cost-effective method to quantify the absorption or ingestion rate in cultured fish species as well as the utilization and adoption of acidifiers consisting of organic acids and their salts as a potential replacement for antibiotic growth promoters are recommended as real and achievable research goals for future.