Particle motion and sound pressure in fish tanks: A behavioural exploration of acoustic sensitivity in the zebrafish.

Underwater sound fields can be complex, both in open water and small tank environments. Here we measured 1) spatial variation in artificially elevated sound levels in a small fish tank for both particle motion and sound pressure. We confirmed that the ratio of pressure and particle motion deviated considerably from what would be expected in theoretical far field environments. We also tested 2) whether the acoustic response tendency of adult zebrafish (Danio rerio) was correlated to the sound field conditions at their position at the moment of sound on-set. We found no correlation between the intensity, quality, or directionality of the behavioural response and the sound pressure or the directivity and ellipticity of particle motion. There was a negative correlation, however, between the tendency to freeze and the particle velocity level. The data and experimental setup provided here may serve a basis to further explore the acoustic world of fish in complex environments and may contribute to the study of potential welfare and conservation issues related to anthropogenic noise.