Aquarium fish that listen to classical music grow more quickly, according to the results of an unusual study by scientists from Greece.
Experts from the Department of Applied Hydrobiology at the Agricultural University of Athens played Gilthead seabream, Sparus aurata, piped-Mozart to see how they responded.
The experiment, which looked at the effects of music under different lighting intensities, saw the scientists playing the bream Wolfgang Amadeus Mozart's 'Romanze-Andante' from K525, or Eine Kleine Nacht Musik, via an underwater speaker.
The young fish that were played the music during the first 89 days of rearing grew better than those that only got to listen to the ambient noise of their aquarium's pumps and aerators.
The fish listened to Mozart every day, from Monday to Friday, but had the weekends off.
"Mozart's music was chosen because it is characterised by pure and single sounds, rhythms and melodies of relatively high frequencies and exerts a calming and almost clear anti-stress effect on humans," the authors wrote in the Journal of Fish Biology.
Gilthead bream are a popular food fish. Picture by Luis Miguel Bugallo Sanchez. Creative Commons.
Enhanced growthThe study showed that the growth of the fish was enhanced in several ways.
"During the first 89 days of rearing, music resulted in enhanced growth.
"Nevertheless, at the end of the experiment (on day 117) no significant differences were found for body mass but music treatment resulted in more homogeneous fish populations than controls."
The study claims that brain neurotransmitter levels were reduced when the exposure to Mozart coincided with brighter lighting, and feed utilisation was better when the music was played in four-hour sessions.
ApplicationsThe scientists believe that fish farmers could use the findings to improve the quality of farmed Gilthead bream:
"The present results provide the initial evidence that music transmission under specific rearing conditions could have enhancing effects on S. aurata growth performance, at least at specific fish sizes.
"Moreover the observed music effects on several aspects of fish physiology (eg. digestive enzymes, fatty acid composition and brain neurotransmitters) imply that music could possible provide even further enhancement in growth, quality, welfare and production."
Previous studies have demonstrated that several different non-natural sounds transmitted to fishes have had "negative or no effects."
Hearing or listening?The scientists added that what the fishes actually perceived when the music was played to them remains unknown:
"Sound transmitted in the present study could have been just perceived as an increase in ambient noise (by 19db), a variation in ambient noise (as music piece chosen had its ups and downs), a novel previously non-existent sound within the tank, shock or enrichment and maybe as music per se."
The same classical piece has been used in several other studies, including one on carp.
For more information see the paper: Papoutsoglou SE, Karakatsouli N, Batzina A, Papoutsoglou ES and A Tsopelakos (2008) - Effect of music stimulus on gilthead seabream Sparus aurata physiology under different light intensity in a recirculating water system. Journal of Fish Biology (2008) 73, 980-1004.