September 23, 2016 — The singing fish mystery has finally been solved – the night humming is triggered by a hormone that tells most animals, including humans, when it is time to go to sleep – melatonin. For humans and most other living creatures, melatonin anticipates the daily onset of darkness. Not for the singing fish, in his case – it affects the males only – it tells him to start his courtship humming.
For much of the animal kingdom, melatonin, which regulates our body clock, is involved in the synchronization of the circadian rhythms of physiological functions including blood pressure regulation, sleep timing, seasonal reproduction, and several others.
About thirty years ago, houseboat dwellers in San Francisco Bay were puzzled by a humming sound that started abruptly in the late evening and would suddenly stop in the morning.
Rumours were rife among the local human population – perhaps the droning hum came from some sinister underwater military exercise, the shifting of the tectonic plates under the sea, or maybe even some enigmatic alien that was communicating with others of its kind.