An experiment reproducing under standard laboratory conditions the pro
cess of active avoidance learning similar to that in natural environme
nt was set up. Before the beginning of a conventional active avoidance
training in a shuttlebox (with visual conditioned stimulus-CS) pre-tr
aining of fishes was conducted using the same apparatus according to t
he same technique,but without CS presentation. After including CS into
training, active avoidance developed fast and mighty. This process co
rresponds to fast learning of the fishes observed in nature.