The detection of pressure fluctuations, sonic audition, is the dominant mode of dipole-source detection in goldfish (Carassius auratus).

Behavioral detection of a low-frequency (40 Hz) vibratory dipole at source distances of 1.5-24 cm was measured by classically conditioned respiratory suppression in goldfish (Carassius auratus). Detection thresholds were compared across distances and before and after ablation of individual octavolateralis sensory channels. Detection thresholds, expressed in units of pressure (SPL), remained roughly constant as distance between the stimulus source and animal increased. Lateral line inactivation, using CoCl2, had no measurable effect on sensitivity, although some other results can be construed as weak evidence for a small contribution of the lateral line to dipole detection when source distances are <or=6 cm (<1 body length). Gas bladder deflation resulted in a large increase in threshold (17 dB), demonstrating that the gas bladder contributes to audition at low frequencies. The present study confirms an auditory role for the gas bladder-enhanced inner ear of goldfish in the detection of low-frequency vibratory sources. Sonic audition (detection of pressure fluctuations) appears to be the dominant mode of dipole-source detection for goldfish when measured by conditioned behaviors in psychophysical experiments.