Comparative Aspects of Calcium Dynamics in Calcified Tissues in the Goldfish Carassius auratus

Abstract

The comparative nature of calcium physiology in bone, scales and otoliths was studied in young goldfish, Carassius auratus. Net calcium uptake by the fish was estimated to be 143 µg/g-body weight/day. Of that, 79% was distributed in bone, 13% in scales, 3.5% in otoliths and 4.5% in soft tissues. Scales showed the highest incorporation of 45Ca per mg-tissue weight after 1 or 2 days in 45Ca-containing water; bone came second and otoliths last. However, 35 days after transfer to non-radioactive water, the order of descending radioactivity had changed to otoliths, bone and scales, reflecting different rates of calcium turnover. In bone, prelabeled 45Ca activity increased for the first 2 days after transfer and then decreased gradually (biological half-life, T0.5=94 days). In otoliths, prelabeled radioactivity consistently increased for 35 days. Scales showed two phases of calcium turnover. They lost about 33% of their prelabeled radioactivity during the first 7 days (T0.5=10.5 days) in non-radioactive water, but thereafter the rate of decrease slowed down greatly (T0.5=210 days). These two phases of calcium turnover were found in the osseous layer (including calcium crystals in the fibrillary plate) of scales, indicating the presence of physiologically labile as well as stable forms of calcium in the layer. © 1983, The Japanese Society of Fisheries Science. All rights reserved.