Requirement of Red Sea Bream for Dietary Na and K

Abstract

Two experiments were conducted to examine the dietary requirement of red sea bream, Chrysopkvys major, for sodium and potassium supplementation. The fish were fed on two test diets with and without sodium supplementation (Exp. I), and potassium supplementation (Exp. II), over a 63 day period at 25℃. At the end of the feeding trial, histopathological examination of the tissues, hematological examinations, and chemical analyses of the liver and vertebrae were performed. No significant differences were recognized between the two groups in each experiment in the following determinations : the growth rate, feed efficiency, condition factor, and hepatosomatic index; the hemoglobin content, hematocrit value, red blood cell count, mean corpuscular hemoglobin, mean corpuscular volume, mean corpuscular hemoglobin concentration, mean corpuscular diameter, and percentage of immature erythrocytes ; the moisture, lipid, and glycogen content of the liver; and the lipid, ash, calcium, phosphorus, magnesium, sodium, and potassium content of the vertebrae. Furthermore, no pathological change was recognized in the organs of fish fed the diets without the sodium or potassium supplement. From these findings, it appears that sodium and potassium supplementation in the diet for red sea bream is not essential, even if these elements are scarcely contained in the diet