Rainbow trout

At the beginning of its introduction, it did not reproduce in the rivers. However, it soon adapted to local conditions and began to reproduce, naturally colonizing sections of rivers and streams where it had never been stocked. It does not hybridize with the native marble trout, but it is an aggressive competitor for food and habitat and a very dangerous rival on spawning grounds, where it appears after the marble trout.

Rainbow trout can be found in the Soča from Vrsnik downstream, in the Koritnica from Kluže downstream, in the lower section of the Učja, in the Nadiža, in the lower section of the Bela, in the Tolminka from the dam in Tolmin (with occasional individuals also in the upper course), in the Idrijca, in the Trebuščica from the confluence with the Jelenk stream, and in the Bača from Klavže downstream (with only occasional individuals in the upper course). It is also often found in tributaries. When feeding, rainbow trout are not selective and will take any available food.

In our waters, they spawn from December to the end of March, sometimes even into April. Rainbow trout can grow up to 80 centimeters in length and reach a weight of up to 8 kilograms.