Color preference of zebrafish (Danio rerio) differs in midday and midnight (2025)

Shadman, A. F.

Abstract

This study aimed to examine whether zebrafish exhibit different color preferences during the day and night under controlled laboratory conditions. Twenty adult zebrafish (3 months old, 1:1 male/female ratio) were housed under a 14:10 h light/dark cycle and tested using a glass plus maze. Four light colors—yellow (647 nm), blue (467 nm), green (532 nm), and red (660 nm)—were presented with equal irradiance (2.25 ± 0.04 µW/cm2). Fish were video-recorded at two time points: midday (12 PM) and midnight (12 AM). Statistical analyses, including chi-square tests and mixed-model analysis, confirmed significant differences in color preference patterns between day and night (P < 0.001). Yellow was consistently the most preferred color, followed by blue > green > red during the day, whereas at night, yellow remained dominant, but the order altered to red > blue > green. These findings highlight that while zebrafish maintain a consistent preference for yellow regardless of time, their ranking of other colors shifts between day and night. According to this study, when evaluating aquatic species’ preferences for light colors, experimental conditions should consider the circadian rhythm.