Dominant males of an Indonesian species of fish turn black during periods of heightened aggression, scientists have discovered. Their blackened markings, which quickly emerge at the start of a conflict, appear to serve as a signal of dominance to other fish.
Celebes medaka (Oryzias celebensis) males with these distinctive black markings were more likely to attack and less likely to be attacked, researchers reported on Dec. 24, 2023 in the preprint repository BioRxiv. The markings appeared within a minute of the onset of a conflict.
