Measurement of five androgens in the blood of immature and maturing male rainbow trout, Salmo gairdneri (Richardson).

Antisera for radioimmunoassay (RIA) against testosterone, 11-oxo-testosterone, 11 beta-hydroxytestosterone, 11-oxo-androstenedione, and 11 beta-hydroxyandrostenedione were raised in female rabbits. The RIAs were tested for their suitability for quantification of the steroids after thin layer chromatography of ether extracts from plasma pools of immature and maturing male rainbow trout. Results from control experiments of the RIAs (buffer blanks, sensitivity, cross reactivity, intra- and inter-assay coefficients of variation, accuracy) were all within a normal range. These RIAs should be helpful tools to test the significance of the hypothesis concerning the "interrenal-liver-gonad axis" which has been proposed to account for the high androgen levels in male trout during high reproductive activity.