Total Replacement of Dietary Fish Oil with a Blend of Vegetable Oils in the Marine Herbivorous Teleost, Siganus canaliculatus

Abstract

To investigate the feasibility of total replacement of dietary fish oil with vegetable oils (VO) and the optimal dietary polyunsaturated fatty acid (PUFA) level in the marine herbivorous teleost Siganus canaliculatus, six isonitrogenous (32 %) and isolipidic (8 %) diets were formulated. Control diet (FO) used fish oil as lipid source, whereas diets VO1-VO5 contained various blends of palm, soybean, rapeseed and linseed oils, in which the dietary PUFA levels were 42.0 %, 38.2 %, 33.8 %, 29.9 % and 27.1 %, respectively. After S. canaliculatus juveniles were fed with the diets for 9 weeks, their growth performance exhibited no significant difference among the dietary groups. The tissue fatty acid profiles in liver and fillet generally reflected the dietary fatty acid compositions, and showed no significant difference among the VO dietary groups. The results suggested that dietary fish oil can be replaced completely by VO without affecting their growth performance. Concerning the effects of the dietary FA profile on the survival rate, HSI and VSI, and PUFA composition in fillets, diets VO1 and VO2 were more favorable compared with diets VO3–VO5. Considering the availability and cost of the VOs, diet VO2 was recommended for practical use in S. canaliculatus.