Do fish speak to each other?

Do they 'speak' if yes, how?

Speaking is one of the most fundamental skills we've learnt when we were young. We use this skill to convey our feelings, thinking and opinion to others, or in other words - communicate by making sound. So here comes the question? Do the underwater dwelling fish speak to each other too like human to express itself? The answer is YES, but not exactly similar to human.

leads to its unique sound production. This concept is similar to playing drums, the sudden contraction of the swim bladder wall causes vibrations which then compresses the air inside. The air inside the bladder vibrates too and produce sound waves. Majority of the sounds produced by this method are short pulses with low frequencies (45 - 60 Hz) or (250 - 300 Hz). As reference, the normal hearing frequency range of human is between 20 Hz and 20,000 Hz.

Why they speak?

Speaking in the fish world might not be as sophisticated as in human world. Based on current scientific researches, most of the sound produced by fish is mainly associated with either reproduction or stressful calls. They can utilize sound production ability to perform mating calls which attract or finding suitable mates for reproduction. Some fishes can utilize sound as cue for synchronization spawning (drum fish) which form a chorus during reproductive season, this sound is usually made by males only. Sound production by fish is sometimes agonistic or aggressive for territorial defense (damselfish), protects food (toadfish), protects nest (toadfish) and predator evasion (catfish). It is found that certain nocturnal planktivorous fish will produce 'pop' sound during feeding to maintain their school size without getting lost in the dark!

Other sound producing methods?

There are two other methods for fish to produce sound. Instead of 'speaking', fish can produce sound through stridulation and through hydrodynamics.

Stridulation is when hard skeletal parts are rubbed together (plucking, strumming or rubbing of rigid body pats together), vibrations and soundwaves are produced due to the scratching and the sound is omnidirectional. Fish stridulatory sound is usually produced by rubbing the teeth together. Hydrodynamic sound is produced when a fish quicky changes its direction or velocity such as tail slapping (Butterfly fish)or head slapping (Sculpin fish). Most of the sound produced by this method is non-intentional and is extremely low frequency. Predators such as shark can detect these hydrodynamic sounds produced by swimming smaller fishes and proceed to tract and hunt them.

In human body, air from the lungs passes through the vocal chord causing it (vocal chord) to vibrate which leads to sound production. In contrast to human, fish have swim bladder to store the gases (human uses lungs), there are special sonic muscles located near or directly on the swim bladder which causes swim bladder to contract and expand, rapidly changing swim bladder volume which

In order to produce sound, the swim bladder must be filled with air first. For some species, the swim bladder is connected to esophagus by a duct. These fishes have to come up and out of the water surface to gulp air, and transfer the air into swim bladder through the duct. For other species which lives deep in the ocean, they would possess rete mirabile (complex of blood arteries and veins lying very close to each other) within the swim bladder wall. During gaseous exchange/breathing, gas that is transferring in the circulatory system can be direct into the swim bladder by rete mirabile which fills up swim bladder with gas. With this adaptation, they don't have to come up all the way from deep ocean to the water surface just to fill up their swim bladder.

Photo of Black drum fish By Smithsonian Environmental Research Center

Shark looking for its next victim... (left)

hoto by Gerald Schömbs on Unsplash