The ballan wrasse lives in warm waters and migrates to the north in the summer. When they return again in the winter because the water in the north is too cold, they sometimes stay awhile in the North Sea. That is why they are occasionally caught by fishermen in the winter. Ballan wrasse like rocks and make their nest in the crevices. This nest is fastened with threads of slime. These fish are born as females but change into males after around ten years.