This small stream, originating in Lake Mainuanjärvi, flows for the greater part of its course in a series of calm pools, interspersed every few kilometres by leisurely rapids. The most interesting white-water fishing area is located along the stream’s middle course, before it enters Lake Oulujärvi.
The angler will find such fishing spots by turning off the Kajaani-Kokkola road (main road 28), approximately 25km from Kajaani, on to the Vuoreslahti road. The Mainuanjoki passes under this road in a turbulent flow through the village of Koskenkylä (Vuoreslahdentie 3312). The former village school lies at the head of the bridge. Today the building serves as the village community centre, under the name of Koskikartano. The most popular stretch of rapid measures approximately half a kilometre in length and around 5 to 10 metres in width. The rapid is not especially rough, running in a leisurely flow as far as Lake Oulujärvi and providing a pleasant mix of fishing. Anglers have free access to the riverside despite the vicinity of the houses. The privacy of summer cottages and other buildings in Koskenkylä village should nevertheless be respected. This also applies to the entire river. Totalling nearly ten kilometres, the fishing area begins below Lake Mainuanjärvi, downstream from main road 5. Along its upper reaches, the river flows mostly through farm fields, parallel to the Kajaani-Kokkola road. There are no signposts to direct anglers to the rapid along the upper reaches, and most roads leading to the river are private driveways.
Fish stock and stock management
Impressive-size rainbow trout are caught in the Mainuanjoki, particularly in the area where it passes through Koskenkylä village. The fishing association stocks rainbow trout several times each summer. The dark-water pools of the river yield pike, while the rapids may also reward the angler with good-size brown trout. Trout in Lake Oulujärvi are able to run up the Mainuanjoki unobstructed, and this migratory population is supported with the stocking of fry. A grayling population was naturalised in the river in the 1990s. Today, grayling are an integral part of the river’s fish stock.