Space-number association in zebrafish

Spatial-numerical associations reflect the tendency to map small numerosities to the left and larger numerosities to the right. Although widely documented in humans and some non-human species, its presence in teleost fish has remained unclear. Here, we investigated whether zebrafish exhibit a spatial-numerical association by presenting fish with a left-right numerical discrimination task in a controlled behavioral assay. Zebrafish showed a reliable leftward preference when selecting smaller numerosities and a rightward preference when selecting larger ones, indicating a systematic coupling between numerical magnitude and spatial direction. These results provide the first evidence of a number-space association in zebrafish and demonstrate that number-space mapping extends to a basal vertebrate lineage. This establishes zebrafish as a tractable model for probing the neurobiological foundations of number-space associations. HighlightsO_LIZebrafish map numerical magnitudes onto left-right spatial positions. C_LIO_LISpatial biases are more robust for small numerosities but still present for larger ones. C_LIO_LIContinuous physical controls disproportionately affect the strength of spatial mapping for large sets. C_LI