The undersea world isn't as quiet as we thought, according to a New Zealand researcher who found fish can "talk" to each other.
Fish communicate with noises including grunts, chirps and pops, University of Auckland marine scientist Shahriman Ghazali has discovered according to newspaper reports on Wednesday.
"All fish can hear, but not all can make sound -- pops and other sounds made by vibrating their swim bladder, a muscle they can contract," Ghazali told the New Zealand Herald.
Fish are believed to communicate with each other for different reasons, including attracting mates, scaring off predators or orienting themselves.
The gurnard species has a wide vocal repertoire and keeps up a constant chatter, Ghazali found after studying different species of fish placed into tanks.
On the other hand, cod usually kept silent, except when they were spawning.
"The hyopothesis is that they are using sound as a synchronisation so that the male and female release their eggs at the same time for fertilisation," he said.
Some reef fish, such as the damselfish, made sounds to attempt to scare off threatening fish and even divers, he said.
But anyone hoping to strike up a conversation with their pet goldfish is out of luck. "Goldfish have excellent hearing, but excellent hearing doesn't associate with vocalisation -- they don't make any sound whatsoever," Ghazali said.
He was to present his findings to the New Zealand Marine Sciences Society conference on Wednesday.