Dietary supplementation with gac (Momordica cochinchinensis) aril powder and oil enhances coloration, hemato-biochemical parameters, and immunity-related gene expression in ornamental goldfish.

Abstract

Background and aim: The use of plant-derived functional feed additives has gained increasing attention as a sustainable strategy to improve fish health and reduce dependence on synthetic pigments and chemotherapeutics in aquaculture. Gac (Momordica cochinchinensis) arils are rich in carotenoids, flavonoids, and other bioactive compounds with recognized antioxidant and immunomodulatory properties. However, their application in ornamental fish nutrition remains largely unexplored. This study compared the effects of dietary supplementation with gac aril powder (GP) and gac aril oil (GO) on growth performance, pigmentation, hemato-biochemical parameters, liver histology, and immunity-related gene expression in ornamental goldfish (Carassius auratus).

Materials and methods: Five isonitrogenous and isolipidic diets were prepared: a control diet without supplementation, GP at 10 and 30 g/kg (GP10 and GP30), and GO at 5 and 10 g/kg (GO5 and GO10). Goldfish (20 fish per tank; three replicates per treatment) were fed the experimental diets to apparent satiation for 10 weeks in a flow-through system. Growth performance, feed utilization, body coloration, tissue carotenoid deposition, hematological and serum biochemical indices, liver histology, and hepatic expression of tumor necrosis factor-alpha (TNF-α), interleukin (IL-1β), IL-10, lysozyme, and heat shock protein 70 (HSP-70) were evaluated.

Results: Neither GP nor GO significantly affected growth performance, feed conversion ratio, protein efficiency ratio, somatic indices, whole-body composition, or liver histology. Nevertheless, dietary supplementation significantly improved protein productive value, with the highest value observed in GP30. GO10 markedly enhanced skin redness, particularly in the abdominal and caudal regions, and significantly increased carotenoid accumulation in muscle, skin, liver, and serum, whereas GP30 produced the highest carotenoid deposition in fins. Both GP and GO increased red blood cell count and hemoglobin concentration, while GO supplementation also elevated white blood cell count. GO10 significantly reduced aspartate aminotransferase, total cholesterol, and triglyceride concentrations while increasing high-density lipoprotein cholesterol. Furthermore, GP and GO upregulated IL-1β, IL-10, and lysozyme expression, with GO10 producing the strongest immunostimulatory response, including approximately 20-, 26-, and 36-fold increases in TNF-α, IL-10, and lysozyme, respectively, whereas HSP-70 expression remained unchanged.

Conclusion: Dietary supplementation with gac aril products, particularly 10 g/kg GO, effectively enhanced pigmentation, carotenoid deposition, hematological and lipid metabolic profiles, and innate immune-related gene expression without compromising growth performance or liver integrity. GO represents a promising natural, multifunctional feed additive that improves the health, coloration, and commercial value of ornamental fish and offers a sustainable alternative to synthetic carotenoids in aquaculture.