Essentiality of dietary calcium supplement in redlip mullet Liza haematocheila

This study was conducted to determine the essentiality of dietary calcium s upplement to redlip mullet Liza haematocheila. Juvenile fish were fed four purified experimental diets containing 2.0 g kg(-1) Ca from calcium lactate (diet 1), no supplemental Ca (diet 2), and 2.0 g and 25.0 g kg(-1) Ca from tricalcium phosphate (TCP, diets 3 and 4), respectively. At the end of the 10-week experiment, growth was significantly lower in fish fed diet 2 than fish fed all other diets. This suggests that redlip mullet do not obtain a dequate Ca from sea water. Fish fed diets 3 and 4 showed growth performance s similar to fish fed diet 1. However, dietary TCP negatively affected bone mineralization of Zn, Mn, K and Fe. The Ca, Zn and Fe levels in liver were low in fish fed TCP-supplemented diets. From these findings, it may be con cluded that a dietary Ca supplement is necessary for redlip mullet. Althoug h this species can use dietary TCP as a Ca source for growth, an easily dig estible Ca (monobasic or dibasic) supplement to a TCP-rich diet is also ess ential to maintain normal mineral levels in tissues.