Abstract
This study was undertaken to determine the availability of calcium (Ca) from seawater and from dietary tricalcium phosphate (TCP) in juvenile Japanese flounder Paralichthys olivaceus. Four semi-purified diets, supplemented with 0.2% Ca from Ca-lactate, no Ca supplement, and 0.2 and 2.5% Ca from TCP, were fed to duplicate groups of fish held in running seawater (26.5-29.0°C) for 10 weeks. The Ca unsupplemented diet gave significantly poor growth compared to the control diet with a 0.2% Ca supplement from Ca-lactate. A low Ca supplement from TCP to the diet gave comparable growth, however, a high Ca supplement from TCP resulted in significantly decreased growth and feed efficiency when compared with the control diet. A high level of Ca from TCP in the diet decreased Zn content of the bone. It is suggested that Ca from seawater is not adequately available to Japanese flounder and an easily digestible Ca supplement to the diet is necessary.
