Abstract: In order to investigate the respiratory metabolism of Portunus trituberculatus, the closed hydrostatic method was used to determine the oxygen consumption rate, ammonia excretion rate and asphyxiation point at the growth period of Ⅵ-Ⅺ. The results showed that the oxygen consumption increased with the late growth periods, the maximum value was 3.950 mg/L at Ⅺ period, the differences were significant among Ⅷ-Ⅺ period (P<0.01); the oxygen consumption rate decreased with the large growth period. The ammonia excretion and ammonia excretion rate increased between Ⅵ-Ⅹ period, and the maximum values were 1.34 mg/L and 0.017 mg/(g.h), respectilely at Ⅹ period. The asphyxiation point increased between Ⅵ-Ⅹ period, and the maximum value was 9.12 mg/L at Ⅹ period.

Key words: Portunus trituberculatus, oxygen consumption rate, ammonia excretion rate, asphyxiation point