Voluntary emergence and water detection in a newly recognized amphibious fish.

Galaxias 'nebula', a small fish which has adaptations for air-breathing but is not known to be amphibious, voluntarily emerged from water and, in an unfamiliar environment, moved preferentially towards an alternative water source. Nebula may thus be considered one of the few truly amphibious fishes, and their ability to detect water provides a selective advantage which aids their survival in unpredictable natural environments.