Researchers observe after-hours natural behavior of lab fish medaka
In a published in Scientific Reports, Osaka Metropolitan University researchers have gained clearer insights into the natural behavior of medaka, small fish that are useful as model organisms in the lab.
Specially Appointed Dr. Yuki Kondo and Professor Satoshi Awata of the Graduate School of Science conducted continuous 24-hour observations of medaka raised in an environment close to their natural habitat and verified when the fish begin their reproductive behavior.
Medaka spawning behavior in a natural environment begins around 1 a.m. and peaks between 2 a.m. and 4 a.m. In addition, courtship behavior was frequently observed between 2 a.m. and 5 a.m. Many other behaviors also started during the late-night hours.
"These discoveries will lead to a review of the experimental conditions for medaka as a model organism and demonstrate the importance of information on the natural ecology of such organisms," stated Dr. Kondo.
More information: Yuki Kondo et al, Courtship and spawning behaviour of medaka in a semi-outdoor environment initiating at midnight, Scientific Reports (2025).
Journal information: Scientific Reports
Provided by Osaka Metropolitan University