Essentiality of dietary calcium supplement in fingerling scorpion fish ( Sebastiscus marmoratus)

Abstract

Essentiality of dietary calcium (Ca) supplement was investigated in fingerling scorpion fish. Four purified diets were formulated with supplementation of 0.2% Ca from Ca-lactate, no supplemental Ca, and 0.2 and 2.5% Ca from tricalcium phosphate (TCP), respectively. Each experimental diet was fed to three replicate groups of fish (mean weight, 0.8 g) for 12 weeks at a water temperature of 24±0.2°C. Significantly lower weight gain was observed in fish fed the Ca-unsupplemented diet compared to the control diet with 0.2% Ca supplement from Ca-lactate. The growth of fish fed the diet with a low level (0.2%) of Ca from TCP was similar to that of fish fed the control diet. However, a high level (2.5%) of dietary Ca from TCP significantly decreased growth. Calcium and phosphorus contents in whole body and vertebrae were similar in fish fed all the diets. A high level of dietary Ca from TCP decreased some trace elements in whole body, liver and vertebrae. Results suggest that scorpion fish do not obtain adequate Ca from seawater for normal growth and a dietary Ca supplement is necessary. Although this species can use a low level of dietary TCP as a source of Ca for growth, excessive dietary TCP depresses growth and negatively affects the contents of some trace elements in tissues. Readily available Ca (mono- or dibasic Ca) supplement to the diet appears to be essential for optimum growth and for maintaining normal mineral levels in tissues of scorpion fish.