Combined prebiotic and multivitamin supplementation enhances growth, survival, and disease resistance of Asian seabass in floating cages

Sustainable alternatives to antibiotics are becoming more crucial in aquaculture for enhancing fish health and performance. This study aimed to evaluate the effects of dietary supplementation with antibiotics and a combination of prebiotics and multivitamins on the growth performance, survival, and disease resistance of Asian seabass ( Lates calcarifer ) cultured in polyethylene floating cages in the Persian Gulf, Qeshm Island, Iran. Over a 32-week trial, 100,000 seabass fingerlings were assigned to one of three dietary treatments: a control diet, a prebiotic/multivitamin-supplemented diet, or an antibiotic-supplemented diet. Key growth parameters, feed conversion ratio (FCR), and pathogens such as Vibrio spp. and Streptococcus spp. in dead fish were assessed through microbiological examination. The combined prebiotic/multivitamin group demonstrated significantly higher final weight (707.2 ± 30.77 g), survival rate (90.13 ± 0.76 %), specific growth rate (1.10 ± 0.01 %/day), and relative growth rate (1308.12 ± 2.69 %) compared to the control and antibiotic groups (P < 0.05). This group also exhibited the lowest FCR (1.08 ± 0.01), indicating superior feed efficiency. In contrast to the other treatments, the prebiotic/multivitamin group showed no signs of Streptococcus agalactiae infection. Our study is among the few that apply these findings to the more diverse and practical setting of open-water cage aquaculture. These findings suggest that the combined prebiotic/multivitamin supplementation is an effective and sustainable alternative to antibiotics in cage-cultured Asian seabass for enhancing growth, feed efficiency, and resistance to S. agalactiae infection. • First report of Streptococcus agalactiae in cage-cultured Asian seabass in Iran. • Prebiotic–multivitamin combination improved final weight, survival, and relative growth in Asian seabass. • Supplemented fish showed the best feed conversion ratio, outperforming the control and antibiotic groups. • Lowest mortality (9.86%) and no S. agalactiae infections seen in the supplemented treatment group. • Results support prebiotic–multivitamin use as a sustainable alternative to antibiotics in cage culture.