Fig. 3. Semi-logarithmic plots of pooled normalized electro-olfactogram (EOG) amplitudes recorded from male tilapia (N=6) in response to pooled urine (A), faeces (B), plasma (C) and bile fluid (D) from pre-ovulatory (filled circles) and post-ovulatory (open circles) females. Comparison of the regression lines revealed significant differences between the elevations (but not the slopes) of the response to urine from pre- and post-ovulatory females and between the elevations (but not the slopes) of the response to faeces from pre- and post-ovulatory females. No differences were found between the responses to plasma (P=0.845) or bile (P=0.923) from pre- and post-ovulatory females. Estimated thresholds of detection are given in the text. ^*P<0.05; ^***P<0.001.