Naturally occurring marble trout have been reared in captivity and stocked to the Soča River since 1995. However, little is known about the interaction between the marble and rainbow trouts in the wild after their release to the river. An international team of scientists in association with the fishing club Idrija will compare farm raised marble and rainbow trout behavior in the Idrijca River using telemetry. Our findings will support marble trout conservation efforts in Slovenia.