The trout is an impressive fish in the salmon family. It is able to live in very small creeks. Some trout remain in creeks, making them very small due to lack of nutrition. Some migrate to the sea and grow to become handsome fish weighing several kilos. They return after a few years out at sea and spawn in their home creek. The trout has suffered from damming of rivers and it is currently severely endangered. The City of Helsinki has implemented many successful creek management operations to improve the condition of creeks for spawning.

Haaganpuro creek (the former Mätäpuro) is the most urban trout creek in Helsinki, with its headwaters in Maunula. The trout has also returned to Mustapuro creek near Itäkeskus. The trout has also successfully spawned in the lower reaches of Mätäjoki River thanks to some creek management work. Young trout have been introduced to these creeks.

The trout is protected, but you may fish for introduced fish when they are at least 50 cm long or 60 cm long in the Vanhankaupunginkoski rapids (2020 rules). Introduced fish can be distinguished by their missing adipose fin.