Effects of coffee silverskin on growth performance, immune response, and disease resistance of Nile tilapia culture under biofloc system

Abstract

The work herein was implemented to ascertain the possible consequences of coffee silverskin (CSS) on the growth, skin mucus, serum immunities, and disease resistance of Nile tilapia (Oreochromis niloticus) raised under biofloc system. Nile tilapia fingerlings (average weight 15.54 ± 0.21 g fish−1) were raised in 15 aquaria (150 L tank−1) at density of 20 fish per tank and fed five different diets: CSS1 (Control), CSS2 (10 g kg−1), CSS3 (20 g kg−1), CSS4 (40 g kg−1), and CSS5 (80 g kg−1) for 8 weeks. Growth rate and innate immune responses were calculated every four weeks, while the challenge test was conducted at the end of the experiment. The results determined that CSS dietary inclusion resulted in improved specific growth rate (SGR) and feed conversion ratio (FCR), compared to that of the control, except in fish fed the CSS5 diet. The optimum dose was recorded in fish fed CSS3. Similarly, fish fed CSS3 resulted in better innate immune responses than those of other incorporated diets, as well as the control. Notably, no significant differences in fish innate immune responses were detected between CSS5 and the control, or CSS2 and CSS4. Similarly, the CSS3 group presented the highest survival rates after the challenge test against Streptococcus agalactiae among all dietary inclusions. In conclusion, the dietary supplementation of 20 g kg−1 CSS (CSS3) may be used as an immunostimulant in tilapia cultured under biofloc system.