Influence of light on feeding anticipatory activity in goldfish.

Most animals when presented with food on a periodic basis develop feeding anticipatory activity (FAA). The objective of the present study was to investigate the synchronization of activity rhythms to light and feeding in single goldfish given a single daily meal and exposed to different light regimes. In the 1st experiment, the group of fish fed at the end of the day showed a longer FAA (228 +/- 27 min) than the group fed 1 h after lights-on (97 +/- 31 min). In the 2nd experiment, goldfish under conflicting zeitgebers, LD (T = 26) and feeding (T = 24) cycles, initially synchronized to the light cycle although feeding time gradually assumed greater importance as the experiment progressed. In the 3rd experiment, after altering the feeding cycles by advancing or delaying feeding time by 4 h in LD 0.25:23.75, most goldfish resynchronized to the feeding stimulus and developed FAA. In conclusion, the authors' results revealed that FAA in goldfish is driven by an endogenous timing system that is entrainable by periodic feeding and influenced by the light regime.