Fluctuation in sex steroids and sex steroid-binding protein during the development and annual cycle of the male common carp, Cyprinus carpio

Abstract

1. 1. Sex steroid concentrations increased during the spawning season in the juvenile and adult male common carp. 2. 2. High levels of plasma sex steroids also were found during the non-spawning season in juvenile fish. 3. 3. No correlation between plasma sex steroid concentrations and SBP binding levels was found in the course of development and annual cycle of male carp. 4. 4. The detection of T concentrations in larval carp occurred earlier than that of T-binding level.