Rapid, accurate time estimation in zebrafish (Danio rerio).

Zebrafish were tested in an appetitive Pavlovian delayed conditioning task. After an intertrial interval of k*T s (k=11.25; T=8, 16 or 32 s), a small, translucent vertical pole was illuminated (CS) for T s. Food was presented at T/2 s. Pole-biting response latencies from CS onset were a linear function of the food delay T/2, with slope approximating unity (proportional timing), and standard deviation proportional to latency (scalar timing). Response latencies tracked changes in food delays even when they changed every other day. These findings are significant because the zebrafish genome has recently been sequenced, opening the door to studies in the genetics of interval timing.