Perca fluviatilis, is a common freshwater fish in Denmark. It is found in almost all lakes and ponds as well as in many streams. Along the shores of the Baltic Sea and in many fjords, the perch goes out into brackish water. It is found all over Europe and northern Asia.
A perch usually grows about 20-30 cm. Along the sides it has 5-7 stripes. The perch rarely grows over 50 cm and 2 kg. It grows very slowly, which means that a perch of 40 cm is usually more than 10 years old.