Requirement of Yellow Croaker Nibea albiflora for Dietary Phosphorus

Abstract

The requirement of dietary phosphorus was investigated in two age groups of redlip mullet, Liza hematochieln. Fish with initial mean weights 3.8 g (zero year-old) and 26.5 g (one yearold) were fed on purified diets containing varying dietary levels of phosphorus (0.3 to 1.1 %). Results from two studies indicated that the available phosphorus requirement of redlip mullet is approximately 0.7%. In both experiments weight gain together with feed efficiency were maximal in fish fed diets containing 0.6-0.7% dietary phosphorus, but further elevation above this level did not result in a better growth. In a zero year-old fish, it was found that the decrease in the dietary P level resulted in the increase in the lipid, and the decrease in Ca, P and crude ash contents of vertebrae. However, no such effect was observed for the one year-old fish. In all groups both serum and bone Ca/P ratio performed values of 3: 1 and 1: 1 in zero and one yearold redlip mullet, respectively, suggesting a predominancy of Ca content in body tissues at early stages. Hence. the change in balance between Ca and P is an age dependent.