Dietary red macroalgae (Halopithys incurva) improved systemic an mucosal immune and antioxidant parameters and modulated related gene expression in zebrafish (Danio rerio)

In the present study, the effects of dietary Halopithys incurva, a red macroalgae species, (0.25, 0.50, 1%) on whole-body serum and skin mucus immune system, antioxidant system and expression of various genes in zebrafish were investigated. At the end of the 8-week study, total protein, total immunoglobulin and lysozyme activities in whole-body serum and skin mucus increased in fish fed H. incurva (P < 0.05). While an increase was observed in superoxide dismutase (SOD), Catalase (CAT) and glutathione peroxidase (GPx) which are antioxidant enzyme activities in whole-body serum and skin mucus, a decrease in malondialdehyde (MDA) levels was detected (P < 0.05). All of the immune-related genes examined, such as Interleukin-1 beta (IL-1β), Tumor necrosis factor-alpha (TNF-α), Interferon-gamma (INF- γ), were upregulated by the addition of 0.5% H. incurva (P < 0.05). While SOD and GPx, which are antioxidant enzyme-related genes, were remarkably upregulated in macroalgae fed fish (P < 0.05), no change was observed in CAT gene expression (P > 0.05). Based on the results of this study, it is considered that the addition of 0.5% H. incurva to the diets of commercially farmed fish will increase their immune and antioxidant defences and may contribute to the aquaculture sector for more sustainability.