When the salmon fry is one year old, it is called a smolt. The smolt has distinct stripes on its sides. The stripes provide good camouflage in flowing river water. The smolt usually lives one to four years in the river. There it hunts for food and good hiding places. The smolt is solitary.

Young salmon between one and four years old are called smolts. The smolt has eight to twelve distinct transverse stripes – so-called smolt marks – on the side of its body. It almost looks as if someone has held the fish's body tightly. Many people therefore call the stripes finger marks. The smolt is a skilled swimmer and thrives best in flowing water. The smolt therefore has long, strong pectoral fins. The finger marks provide good camouflage in the river.

Parr keep to themselves and fight other parrs for both food and good hiding places. Parrs find food in the river all year round. As long as the river water is not too warm (over 24 degrees) or too cold (under 6 degrees), they will grow. But they do not grow that fast. It can take four years for the parr to grow as long as a ballpoint pen, but in some places it takes less time.

As long as the parr marks are visible, the salmon is called a parr. When the stripes disappear, it is a sign that the parr will soon leave the river to go to the sea. When the salmon leaves the river, it is called a smolt.

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