Daily changes in blood serum levels of 17beta-estradiol and 11-ketotestosterone in the mature carp cyprinus caprio L.

Daily changes in blood serum levels of 17 beta-estradiol and 11-ketotestosterone in the mature carp Cyprinus carpio were investigated. Fish were kept under natural light conditions (LD = 16:8) water temperature about 19 degrees C. Females and males were divided into 2 groups respectively. Each group was sampled every 4 h during 24 h beginning at 08:00 (group 1) and 10:00 (group 2). The 17 beta-estradiol assay included a chromatographic step which increased the specificity of the measurement while in 11-ketotestosterone assay a specific antibody was used, having a low cross reactivity with testosterone (1.1%). Data obtained in this work were statistically analyzed using cosinor circle with error ellipses. The highest levels of estradiol (0.46-0.58 ng/ml) were observed between 09:00 and 11:00 and of 11-ketotestosterone (2.09-3.00 ng/ml) between 10:00 and 12:00. It was proved statistically that changes in the estradiol and 11-ketotestosterone levels during 24 h are of circadian rhythm type. The problem of hormonal changes during 24 h, connected with sexual maturation of fish, is discussed