Interstitial movement and emergence of barbel Barbus barbus free embryos and larvae

The movement of barbel Barbus barbus free embryos in the interstitial zone and the timing of larval emergence were studied for 12 days in an artificial stream. After egg fertilization (day 1), hatching occurred on day 6, downstream interstitial movements of free embryos on day 9 and emergence and downstream movement of all larvae on day 12, with density of free embryos decreasing as day of emergence approached. The results suggest that a memory‐based response of B. barbus to environmental conditions, previously observed in 0+ year juveniles, begins at an early age.