Abstract <p>The results of research on spontaneous alternation and changing patterns in the exploratory behavior of roach are presented. Larvae, one-month old, and four-month old roach juveniles use two behavioral models in a plus maze. The younger roach juveniles move around the perimeter of the maze and perform shuttle movement between any two arms. Four-month-old juveniles use moving around the perimeter of the maze more often than the other age groups studied. Тhe proportion of shuttle movements does not depend on the age. The level of spontaneous alternation in one-month-old juveniles is significantly lower than the random level. Larvae and four-month old juveniles show a random level of spontaneous alternation. This depends on the pattern behavior that fish prefer to use. In general, as the fish grow older, the exploratory behavior of the roach seems to become more effective.</p>