Research Article: Growth performance and energy budget of the yellowfin seabream, Acanthopagrus arabicus (Iwatsuki, ۲۰۱۳) affected by the combined effects of water temperature and salinity

A ۵۶-day research was carried out to determine the interactive effects of water temperature (WT) and salinity (WS) on physiological responses of yellowfin seabream, Acanthopagrus arabicus (Iwatsuki, ۲۰۱۳) (۱۰.۰±۰.۲ g). Three salinities (S; ۱۲, ۳۵ and ۵۰ ‰) and four temperatures (T; ۱۶, ۲۳, ۳۰ and ۳۵°C) were selected to design ۱۲ experimental treatments. The husbandry system consisted of thirty-six ۳۰۰-L cylindrical polyethylene tanks that were filled with ۲۵۰ L of water. Each treatment had three replicates (tanks) containing ۲۰ fish in each tank. Fish were handfed on a commercial feed (۴۴۰ g kg-۱ crude protein and ۱۸۰ g kg-۱ crude fat) twice daily at visual satiation. Five fish from each tank were transferred into an experimental chamber to evaluate their oxygen consumption and ammonia excretion. There was a positive correlation between fish oxygen consumption and WT (r=۰.۵۹۴; p=۰.۰۰۱). In addition, there was a negative relationship between WS and ammonia excretion (AE) (r = -۰.۸۶۵; p=۰.۰۲۹), meanwhile the relationship between WT and AE was positive (r=۰.۴۲۲; P=۰.۰۱). Growth parameters were significantly affected by WT, WS and their interactions so that the highest final body was recorded in the highest temperature and salinity treatment. On the other hand, the lowest body weight was observed in the lowest WT (i.e., ۱۶℃) irresponsive to WS. The moisture level in the whole body was affected by WT (p=۰.۰۱۲). The crude lipid in the whole body was influenced by only WS (p=۰.۰۴). The ash content in the whole body was profoundly affected by WT (p=۰.۰۰۰۱), WS (p=۰.۰۰۰۱) and their interaction effect (p=۰.۰۴). The energy content of the whole body was only affected by WT (p=۰.۰۲۵). The energy budget of fish was influenced by WT (p=۰.۰۰۰۱) and its interaction with WS (p=۰.۰۱۵). In summary, the present findings indicated that the preferred WT for A. arabicus is between ۳۰ to ۳۵°C in brackish water.

کلیدواژه ها:

Acanthopagrus arabicus ، Bioenergetics ، Euryhaline fish ، Feed utilization ، Thermal requirements