To investigate roles of the longchain fatty acid elongase 2 and 5 (elovl2,elovl5) genes played in biosynthesis of longchain polyunsaturated fatty acids (LC-PUFA) in loach (Misgurnus anguaudatus),fulllength cDNA sequences of the loach elovl2 andelovl5 were cloned and their expression patterns in different tissues were analyzed in this study. Functional characterizations of the loach elovl2 and elovl5 in synthesis of fatty acids were studied by heterologous expression in Saccharomyces cerevisiae in vitro. Loach were fed with three experimental diets containing fish oil (FO),camelina oil (CO) and soybean oil (SO),respectively,for 8 weeks to evaluate the effects of different dietary lipid sources on expressions of the loach elovl2 and elovl5. The results showed that the open reading frame (ORF) of the loach elovl2 and elovl5 was 888 bp and 876 bp,encoding 295 and 291 amino acids,respectively. Phylogenetic analysis showed that they clustered closely with the zebrafish elovl2 and elovl5 and sequence comparison showed that they were highly conserved in vertebrates,containing the special structure of longchain fatty acid elongases. The expression levels ofelovl2 and elovl5 were highest in the liver. ELOVL2 elongated C20-22 PUFA,while ELOVL5 was able to elongate C18:20 PUFA,having no effect on C22 PUFA. The content of n-3 PUFA in the liver and muscle and 20∶5n-3 in the muscle increased significantly,while 22∶6n-3 in the liver and muscle did not increase significantly in the CO group. In addition,expressions of the loachelovl2,elovl5,scd and srebp1c in the liver were significantly increased. In conclusion,elovl2 and elovl5 played an important role in regulating the synthesis of LC-PUFA and CO used in diet could promote the accumulation of n-3 PUFA in loach.