Postprandial Ammonia Excretion and Oxygen Consumption Rates in Olive Flounder Paralichthys olivaceus Fed Two Different Feed Types According to Water Temperature Change

摘要

Postprandial ammonia excretion and oxygen consumption in olive flounder Paralichthys olivaceus fed two different feed types, moist pellet (MP) and expanded pellet (EP) diets, to satiation were determined at 12°C, 15°C, 20°C, and 25°C for 48 h. Theammonia excretion and oxygen consumption rates increased with increasing water temperature. However, the postprandial times for the maximum rates of ammonia excretion and oxygen consumption were shortened from 12 h to 6 h after feeding with increasing water temperature. The ammonia excretion and oxygen consumption rates of the fish fed EP were significantly higher (P < 0.05) than those fed MP at 12 h post-feeding both for 12°C and 15°C. The highest (P < 0.05) weight-specific ammonia excretion rates at 12°C were observed in the fish fed EP and MP at 12.1 mg NH3-N kg~(-1)h 1 and 8.7 mg NH3-N kg~(-1)h~(-1), respectively, for 12 h and 9 h after feeding. The highest (P< 0.05) weight-specific oxygen consumption rates at 12°C were observed in fish fed EPand MP at 116.4 mg kg-'lr~(-1) and 101.0 mg kg-'h~(-1), respectively, for 12 h after feeding. The highest ammonia excretion rates at 25°C in the fish fed EP and MP increased to 16.9 mg NH,-N kg~(-1)h-1 and 18.3 mg NH,-N kg~(-1)h~(-1), respectively, for6 h after feeding. The highest (P < 0.05) weight-specific oxygen consumption rates at 25°C were observed in fish fed EP and MP at 184.3 mg O, kg~(-1)h~(-1) and 197.3 mg O, kg~(-1)h~(-1), respectively. These data are valuable for the design of biofilters and development of effluent treatment technologies for the land-based flounder farms.