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To determine the optimum P requirements of taimen (Hucho taimen), the present study investigated the effects of diets supplemented with different levels of inorganic P (NaH2PO4) on growth, proximate composition, blood chemistry, and mineralization in juvenile taimen. Triplicate groups of fish (mean initial weight 15.39 ± 0.28 g) were fed, until satiation, with different diets containing graded levels of digestible P (0.22, 0.40, 0.55, 0.74, 0.90, and 1.07%), for 84 days. Weight gain, feed conversion ratio, and protein retention were significantly (P 0.05). With increasing dietary P levels, P retention and whole-body lipid content decreased from 75.41 ± 7.06 to 36.41 ± 3.30% and from 3.23 ± 0.13 to 2.74 ± 0.25%, respectively, whereas vertebrae ash and plasma P content increased from 43.68 ± 0.23 to 52.09 ± 0.28% and from 2.18 ± 0.14 to 3.98 ± 0.23 mmol L−1, respectively. Using a broken-line regression model that incorporated measurements of P digestibility, feed efficiency, and normal whole-body and vertebrae P content, the dietary requirement of digestible P was determined to be approximately 0.5% for taimen.

This study was conducted to evaluate the effect of tank colour on growth and survival of taimen Hucho taimen larvae. Larvae (initial weight 0.11 ± 0.01 g, 21 days after hatching) were cultured in the water flow-through system. Fifteen aquaria (200 L per aquarium) were randomly allocated into triplicate groups of 500 larvae. The outsides of the tanks were covered in red, blue, yellow, white, or black sheeting. Larvae were fed eight times a day by hand to apparent satiation. The experiment was conducted for 56 days. The results showed that the specific growth rate was significantly affected by tank colour, which was higher in the yellow tank than that of the tank (black or red) (P 0.05). The highest feed intake was observed in fish reared in the yellow tank, followed by that of the white, blue, or black tank, and the lowest was in fish in the red tank. In conclusion, the light-coloured tank (yellow or white) was optimum for rearing taimen larvae based on the growth performance.