In the present paper, we investigated the molecular cloning and functional characterization of elongase of very long chain fatty acid (elovl) and fatty acyl desaturase (fads) genes in a marine teleost, Nibea diacanthus. The elongase cDNA sequence encoded a polypeptide of 294 amino acids exhibiting Elovl5 activity, which effectively elongated both C18 (18:2n−6, 18:3n−3 and 18:3n−6) and C20 (20:4n−6 and 20:5n−3) polyunsaturated fatty acids. The desaturase cDNA sequence specified a polypeptide of 445 amino acids indicating Δ6 desaturation activity, which coul converted C18:2n−6 and C18:3n−3 to C18:3n−6 and C18:4n−3, respectively. Tissue distribution analysis by quantitative real-time PCR revealed that the elovl5 was primarily expressed in intestine and liver, while the fads2 was mainly expressed in liver and brain. These results increase our knowledge of the ability of endogenous highly unsaturated fatty acids (HUFA) biosynthesis in marine carnivorous fish.Guangdong Oceanic and Fishery Science and Technology Foundation (No. A201005D06-1).