Fig. 4. Urination rates of male tilapia in isolation and in the presence of pre- or post-ovulatory females. Histograms showing the rates of urination of sham-operated (A) and anosmic (B) males in isolation (control; open bars) and in the presence of a pre-ovulatory (black bars) or post-ovulatory (grey bars) female (N=6). Different letters indicate significant differences (P<0.01).