en aquaculture aquaculture پژوهشي Orginal research papers This study evaluated the effects of diets containing various carbohydrate-to-lipid (CHO L^-1) ratios on growth performance, nutrient utilization body indices and hepatic lipogenic enzyme (malic enzyme, 6-phosphogluconate dehydrogenase and fatty acid synthase) activities. Triplicate groups of <em>Pangasianodon</em> <em>hypophthalmus</em> fingerlings were fed eight isoenergetic and isonitrogenous diets with different carbohydrate-to-lipid ratios (0.51, 0.79, 1.12, 1.79, 2.41, 3.24, 4.43 and 7.62). Higher body fat deposition and lower growth performance were observed in <em>P. hypophthalmus</em> fingerlings fed with high-lipid diet than those fed with high-carbohydrate diet. The fish fed the diet with 7.62 CHO L^-1 ratio exhibited significantly (<em>p</em><0.05) higher hepatosomatic index compared to those fed higher lipid diets (0.51 and 0.79). High dietary carbohydrate level significantly increased (<em>p<</em>0.05) the activities of malic, 6-phosphogluconate dehydrogenase and fatty acid synthase enzyme. Based on the second-order polynomial regression analysis of weight gain, the optimal dietary carbohydrate and lipid contents for <em>P. hypophthalmus</em> fingerling were 304 and 103 g kg^&minus;1, respectively, which correspond to a dietary CHO L^-1 ratio of 2.95. Striped catfish, Carbohydrate-to-lipid ratio, Lipogenesis, Fat deposition 1818 1827 http://jifro.ir/browse.php?a_code=A-10-2472-1&slc_lang=en&sid=1 M. Asemani mehdi.asemani@yahoo.com 100319475328460035554 100319475328460035554 Yes Iranian Fisheries Science Research Institute, Agricultural Research,Education and Extension Organization, Tehran, Iran A. Sepahdari 100319475328460035555 100319475328460035555 No Iranian Fisheries Science Research Institute, Agricultural Research,Education and Extension Organization, Tehran, Iran M. Hafezieh 100319475328460035556 100319475328460035556 No Iranian Fisheries Science Research Institute, Agricultural Research,Education and Extension Organization, Tehran, Iran Sh. Dadgar 100319475328460035557 100319475328460035557 No Iranian Fisheries Science Research Institute, Agricultural Research,Education and Extension Organization, Tehran, Iran