A Perch (Ahven in Finnish) is one of the most commonly caught fish wheather you are fishing on a river, ocean, or lake. Perches weigh almost the same as breams (around 1/2 lb) and are only bigger than roaches.
Their low cost can make them a decent stopgap food to be bought from settlements if attempts to get other sources of food have been unsuccessful. More recently, perch have a default weight of about 1.25 lbs.