The expression of dock genes in vertebrates is widespread and not restricted to classical dock structures(1,2). The expression of the Clock gene in zebrafish shows a strong circadian oscillation in many tissues in vivo and in culture, showing that endogenous oscillators exist in peripheral organs(3). A defining feature of circadian clocks is that they can be set or entrained to local time, usually by the environmental light-dark cycle(4,5). An important question is whether peripheral oscillators are entrained to local time by signals from central pacemakers such as the eyes or are themselves directly light-responsive. Here we show that the peripheral organ docks of zebrafish are set by light-dark cycles in culture. We also show that a zebrafish-derived cell line contains a circadian oscillator, which is also directly light entrained.