The age and rate of growth of the flounder from inshore shallow waters of the Gulf of Gdansk (from shore to 1-m depth) have been investigated. Mainly the flounder from 0 and 1-year age group exists in this zone. Flounders from 0-year age group enter shallow waters of the Gulf of Gdansk in June or July. They stay in this area till the end of the year. Flounders from 1-year age group are represented in the investigated zone all year. Bigger individuals from this group migrate into deeper waters.