Influences of spent coffee grounds on skin mucosal and serum immunities, disease resistance, and growth rate of Nile tilapia (Oreochromis niloticus) reared under biofloc system

The study was executed to find out the potential effects spent coffee ground (SCG) on Nile tilapia's skin mucosal and serum immunities, disease prevention, and growth rate reared in a biofloc system. Nile tilapia fingerlings (average weight 15.25 ± 0.07 g) were disseminated into 15 aquaria (150 L tank−1) at a density of 20 fish per aquarium and treated five diets: SCG1 (control), SCG2 (10 g kg−1), SCG3 (20 g kg−1), SCG4 (40 g kg−1), and SCG5 (80 g kg−1) for eight weeks. A Completely Randomized Design (CRD) with three replications was applied. Growth rate, skin mucus, and serum immunities were quantified every 4 weeks; whereas the challenge study was conducted at the termination of the feeding trial. The outputs indicated that dietary incorporation of SCG give rise to the enhancement of SGR and FCR in comparison with the control, with best levels noted in fish fed SCG2 diet. Similarly, significant enhancements in skin mucosal and serum immunities were revealed in fish treated SCG2 over the control and other SCG diets. Likewise, higher survival rates against Streptococcus agalactiae were displayed in fish fed SCG, with the maximum level displayed in the fish treated SCG2. In conclusion, dietary supplementation of SCG2 (10 g kg−1) can be potential used as immunostimulants in tilapia aquaculture. •Growth and feed utilization improvements were noted in Nile tilapia fed SCG2 (10 g kg−1).•Skin mucus and serum immunities were enhanced in fish fed SCG2 (10 g kg−1).•The highest disease resistance against S. agalactiae was noted in Nile tilapia fed SCG2 (10 g kg−1).