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The objective of this experiment was to determine the effects of two levels of vitamin E (100 and 300 mg/kg diet) along with two levels of lipid (9 and 14%) and their interaction on growth performance of Indian white shrimp and consequently to evaluate the fatty acid composition and lipid stability of its muscle tissue during frozen storage. Growth of juvenile Indian white shrimp was not significantly affected by dietary vitamin E and lipid levels. Muscle lipid content of shrimp fed diets with 14% lipid was significantly higher than that of with 9% lipid. Obvious effects of the increase in dietary lipid level on muscle fatty acid composition were significant decrease in proportion of 16:0 and increase in proportion of 20:5n-3. The content of vitamin E concentration in shrimp muscle reflected dietary vitamin E concentration and ranged from 6.68 to 14.8 mg/kg muscle corresponding to two (100 and 300 mg/kg) levels of vitamin E in fish diet, respectively. Subsequently, results showed that by increasing the concentration of vitamin E from 100 to 300 mg/kg in diet, the rate of lipid oxidation in the muscle tissue during frozen storage was reduced and, as a result, caused higher HUFA retention in muscle of shrimp fed diet with high lipid level.

A 3 9 5 factorial design including three lipid levels (100, 130 and 180 g kg À1 diet, based on dry matter) and five dietary protein levels (370, 420, 470, 520 and 570 g kg À1 diet, based on dry matter) was conducted to investigate the optimum dietary lipid and protein requirements for Rutilus frisii kutum fingerlings. Triplicate groups of 80 kutum (500 ± 60 mg initial weight) were stocked in 250-l tanks and fed to apparent satiation thrice daily for 8 weeks. The results showed that the growth performance and feed utilization were significantly (P < 0.05) affected by dietary protein and lipid levels. Weight gain, specific growth rate and feed conversion ratio of kutum improved significantly with increasing protein level from 370 to 470 g protein kg À1 diet, but there was a significant decrease in growth parameters with increasing protein level from 470 to 570 g protein kg À1 diet. Also, the higher values of weight gain, specific growth rate and better feed conversion ratio were observed for fish fed diets containing 130 g kg À1 lipid diet. The results of this study showed that diet containing 420 g kg À1 protein and 130 g kg À1 lipid with a P:E ratio of 19.22 mg protein kJ À1 of gross energy is optimal for kutum fingerlings.

Kutum Rutilus frisii kutum is known as a valuable commercial species in the southern part of Caspian Sea. Artificial rearing of fry has been introduced as an alternative to supply kutum fry in order to restock the kutum population in the Caspian Sea. The aim of this study was to find the suitable time to transfer kutum larvae from live food to artificial feed. The experiment began on day 3 post-hatching and lasted for 21 days. Mean initial weight of larvae was 4.5 mg. Five experimental groups including Group A (zooplankton alone for 21 days), Group B (12 days zooplankton ? 9 days artificial feed), Group C (8 days zooplankton ? 13 days artificial feed), Group D (4 days zooplankton ? 17 days artificial feed) and Group E (artificial feed alone for 21 days) were considered for this experiment. According to the obtained results, the specific growth rate of kutum larvae varied from 8.01 to 13.58% day -1 , and the highest and lowest specific growth rate were found in A and E treatments, respectively. The lowest mean body weight (24.6 mg) was found in larvae fed on artificial feed for 21 days. However, survival rates of kutum larvae fed mixed zooplankton for 8 and 12 days (85.83 and 89.33%, respectively) were comparable with those of larvae fed live food during the entire experiment (91.6%). The lowest survival rate (69.16%) was found in larvae fed artificial feed during the entire experiment.

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