The marble trout is a large-sized salmonid found both in alpine lakes and in subalpine lakes on valley floors and on the plains.
At European level, this species is diminishing, mostly because of the ongoing destruction and fragmentation of its habitats, and due to crossbreeding with another salmonid species, the brown trout (Salmo trutta fario). For these reasons, the marble trout has been included in the red list of threatened species compiled by the International Union for the Conservation of Nature (IUCN) and is mentioned in Annex II to the Habitats Directive.
Based on this status, conservation initiatives for this species have a high priority rating.
In the Gran Paradiso National Park, the marble trout has still been found in recent times in few watercourses, such as the Piantonetto, Campiglia and Forzo streams, which provide an ideal habitat for this species.
On the other hand, large brown trout populations constitute a threat to the survival of the marble trout, in that the two species may crossbreed and produce fertile offspring.