BEHAVIORAL AND ENDOCRINOLOGIC RESPONSES OF MATURE MALE GOLDFISH TO THE SEX-PHEROMONE 17-ALPHA,20-BETA-DIHYDROXY-4-PREGNEN-3-ONE IN THE WATER

The behavioural response of spermiated male goldfish to the sex pherom one 17 alpha,20 beta-dihydroxy-4-pregnen-3-one (17 alpha,20 beta-P) in the ambient water was measured using a computerized video-image analy sis system, The position and spontaneous locomotor activity of single spermiated male goldfish were continuously recorded in an artificial s tream, 17 alpha,20 beta-P (final concentration 10(-11) moll(-1)) was s upplied to one half and its ethanol carrier to the other half of the t est area. The results showed that the fish spent significantly less ti me in water scented,vith 17 alpha 20 beta-P than in control water, Mor eover, both the spontaneous locomotor activity and the gonadotropin II concentration in the plasma increased significantly because of contac t with 17 alpha,20 beta-P in the ambient water, The swimming speed was unchanged, whether the fish resided in the 17 alpha,20 beta-P section or in the section without 17 alpha,20 beta-P added, In view of the co mplex dual hormone-pheromone system in goldfish, the possibility of an additional function of 17 alpha,20 beta-P is discussed, Because the r elease of the pheromone 17 alpha,20 beta-P occurs before ovulation and the level then drops drastically, we suggest that the avoidance react ion observed allows the sexually mature male to avoid misdirected cour ting of non-ovulated females and thus to continue its search for an ov ulated female.