Oncorhynchus mykiss
The Rainbow Trout
The Sport Fish for Everyone
The Rainbow Trout (Oncorhynchus mykiss), called Kirjolohi in Finnish, originally comes from North America and is now the most widely stocked sport fish in Finland. In hundreds of managed lakes and rapids, it offers accessible, exciting fishing for beginners and experienced anglers alike.
The Finnish put-and-take system (Koskikalastus) makes trout fishing particularly straightforward: buy a licence, cast your lure, start catching. The Rainbow Trout is an aggressive biter, fights spectacularly on the line and delivers first-class table fare — the perfect introduction to the Finnish fishing experience.
Unlike the native Brown Trout, the Rainbow Trout does not reproduce naturally in Finland. Stocks are maintained exclusively through regular stocking. This means: no closed season, no minimum size — but also the responsibility to support sustainably managed waters.
Seasonal Data
The Rainbow Trout is most active in summer — bite activity in stocked waters peaks between June and August.
Diet Spectrum
The Rainbow Trout is an opportunistic omnivore. In stocked waters, pellets make up a large part of the diet; in rapids, insects and larvae dominate.
Growth by Age
Rainbow Trout grow quickly, especially in managed waters with a good food base. Most stocked fish are caught at 2-4 years of age.
| Age (Years) | Length | Weight | Relative Size |
|---|---|---|---|
| 1 | 15 cm | 35 g | 23% |
| 2 | 25 cm | 160 g | 38% |
| 3 | 33 cm | 380 g | 51% |
| 4 | 40 cm | 700 g | 62% |
| 5 | 48 cm | 1.2 kg | 74% |
| 6 | 55 cm | 1.8 kg | 85% |
| 7 | 60 cm | 2.5 kg | 92% |
| 8+ | 65 cm | 3.2 kg | 100% |
Habitat Requirements
Water Temperature
Tolerates warmer water than Brown Trout but prefers cool, oxygen-rich waters.
Oxygen
High oxygen demand, especially in the warmer summer months. Prefers current-rich sections.
Current
A current-loving fish in its natural state. In Finland, often stocked in rapids (Koski).
Stocking Density
As it does not self-reproduce in Finland, regular stocking is crucial for good catches.
Water Depth
In rapids, prefers mid-depth. In lakes, holds at 1-3 m depth.
Food Supply
Opportunistic feeder. Supplemented by pellets in stocked waters, by natural food in wild waters.
Fishing Techniques for Rainbow Trout in Finland
The Rainbow Trout is a rewarding target — it strikes a wide variety of lures and is less wary than wild Brown Trout. In Finnish rapids and stocked lakes, various techniques come into play.
In the classic Koski waters, spin fishing with small spoons and spinners is the most popular method. Fly anglers find ideal conditions for wet and dry flies in the rapids. At calmer lakes, float fishing with worm or bait paste is a reliable option.
Spin Fishing
May — OctoberSmall spoons (3-7g) and spinners in rapids and stocked lakes. The most versatile method for Rainbow Trout in Finland.
Fly Fishing / Rapids
May — SeptemberWet and dry flies in the Koski waters. Especially effective during insect hatches. Streamers for larger specimens.
Float Fishing
June — AugustWith worm, paste or PowerBait under a float. Ideal for families and beginners at managed lakes.
Ice Fishing / Pilkki
December — MarchVertical jigging through the ice in stocked lakes. With small jigs and maggots — a winter tradition in Finland.
Where to Catch Rainbow Trout in Finland
From the rapids of central Finland to the put-and-take lakes in the south — Rainbow Trout are available throughout Finland.
Central Finnish Rapids
62.5°N, 25.8°EKoskenkalastus tradition
The heartland of Finnish rapids fishing. Dozens of managed Koski waters with regular stocking. Classic spin and fly fishing in scenic rapids.
Kuusamo Region
66.2°N, 29.2°EKitkajoki & Oulankajoki
Spectacular rapids in the wilderness of northeastern Finland. The Kitkajoki and Oulankajoki rivers offer first-class trout fishing in pristine surroundings. Brown Trout and Grayling as bonus catches.
Isojoki
62.1°N, 21.9°EWestern Finland's top trout river
A mid-sized river on the west coast with excellently managed rapids. Regular stocking of Rainbow Trout and good infrastructure for anglers.
Put-and-Take Lakes Nationwide
61.5°N, 24.0°EHundreds of managed waters
Managed lakes and ponds with regular Rainbow Trout stocking are scattered across Finland. Ideal for families and beginners — often with campfire sites and lean-to shelters.
Put-and-Take — How the Stocking System Works
Tip: Check the local regulations of each water body. Some operators set their own bag limits to ensure quality fishing.