This paper deals with the age determination in Anisotremus interruptus by reading of scales that allowed the identification of 9 age groups. The width of the growth rings diminishes as the age increases. The growth of the scales is proportional to the fish growth. The period of highest growth rate happens during the first year of life. During the first year A. interruptus grows 12.52 cm, the second year 4.95 cm and the third, 4.60 cm. The strategy of the quick growth during the first year of life allows A. interruptus to diminish the natural mortality.