Five zebrafish were trained to approach a target using a fully automated training procedure.
During a training session, if the distance between the fish and the target was closer than an
arbitrarily set distance, the approach response was reinforced by food. The fish continued to
respond under this reinforcement contingency and the distance criterion could be shortened
up to eighty times within a 1 h session. The initial distance limit was then shortened for the
next test training session. Once the initial distance criterion was reduced to a final minimum …