This study was designed to compare the effect of two exchange rates （ERs; 0.5 m^3 feed/kg and 1.5 m^3 feed/kg） in re-circulating aquaculture systems （RAS） on water quality and fish growth profiles on fish stocks ...This study was designed to compare the effect of two exchange rates （ERs; 0.5 m^3 feed/kg and 1.5 m^3 feed/kg） in re-circulating aquaculture systems （RAS） on water quality and fish growth profiles on fish stocks （200 indiv/m^3 of 251.4 g e 20.67 g） of gilthead bream, Sparus aurata. Water quality, fish growth, specific growth rate （SGR） and feed conversion ratio under the two ERs were examined for a period of six months. Inorganic nutrient in RAS, temperature, dissolved oxygen and pH were measured daily. Feeding regime effect was also determined on the fish quality and organoleptic characteristics and thus opts to energy optimization of the system. The fish reared under the 1.5 m^3 feed/kg ER demonstrate enhanced growth, the daily SGR and the conversion ratio. Sensory test analysis revealed differences in the organoleptic characteristics between the two experimental fish stocks with considerably high acceptance scores for fish reared at high ER. Nutrient concentrations： ammonia, nitrate, nitrite and phosphate were lower in RAS of the highest ER when compared to those reared under the 0.5 m3/kg feed. Results suggest an ER of 1.5 m^3 feed/kg improved both fish quality and growth profile of the gilthead bream.展开更多
文摘This study was designed to compare the effect of two exchange rates （ERs; 0.5 m^3 feed/kg and 1.5 m^3 feed/kg） in re-circulating aquaculture systems （RAS） on water quality and fish growth profiles on fish stocks （200 indiv/m^3 of 251.4 g e 20.67 g） of gilthead bream, Sparus aurata. Water quality, fish growth, specific growth rate （SGR） and feed conversion ratio under the two ERs were examined for a period of six months. Inorganic nutrient in RAS, temperature, dissolved oxygen and pH were measured daily. Feeding regime effect was also determined on the fish quality and organoleptic characteristics and thus opts to energy optimization of the system. The fish reared under the 1.5 m^3 feed/kg ER demonstrate enhanced growth, the daily SGR and the conversion ratio. Sensory test analysis revealed differences in the organoleptic characteristics between the two experimental fish stocks with considerably high acceptance scores for fish reared at high ER. Nutrient concentrations： ammonia, nitrate, nitrite and phosphate were lower in RAS of the highest ER when compared to those reared under the 0.5 m3/kg feed. Results suggest an ER of 1.5 m^3 feed/kg improved both fish quality and growth profile of the gilthead bream.
