Effects of dietary arachidonic acid on growth, gonadal development, and tissue fatty acid composition in the hermaphroditic swamp eel (Monopterus albus)

10-week dietary arachidonic acid (ARA) feeding trials were conducted in 14-month-old swamp eel (Monopterus albus) to evaluate the effects on growth performance, gonadal development, tissue fatty acid profile, and gene expression related to lipid metabolism. The results showed that swamp eels fed diets supplemented with 1.4% or 2.8% ARA had a significantly higher weight gain rate (WGR) and specific growth rate (SGR) than those fed the control diet. Dietary supplementation with ARA improved oocyte development and maturation. Higher gonadosomatic index (GSI) was detected in 1.4% and 2.8% ARA groups. ARA supplementation delayed sexual reversal in females. The ARA content in the muscle, liver and gonads increased with increasing dietary ARA concentration; however, ARA supplementation significantly reduced the transcriptional expression of lipid metabolism-related genes in the gonads, such as fad2, pla2g4a, and elovl5. Serum alanine aminotransferase (ALT) levels in the ARA 1.4% group were significantly lower than those in the control and ARA 2.8% groups. Total cholesterol (T-CHO) and triglyceride (TG) levels were significantly lower in the 1.4% and 2.8% ARA groups than in the control group. Catalase (CAT) and high-density lipoprotein cholesterol (HDL-C) increased with dietary ARA concentrations. This study found that dietary ARA is important for improving growth, Ovarian development, and antioxidant capacity in swamp eels.