In the video and in the photo you can see two specimens of male trout while side by side they feed in peace, without fighting each other. This happens because they are not yet in the reproductive period, otherwise we would see them as rivals and fighters.
In fact, it is known that in salmonids the reproductive period begins with the migration of the females towards the spawning sites. Well, the ascent of the female does not occur alone, quite the contrary: it is often followed by a “procession” of males in reproductive competition.
In these males, scientists have observed at least three types of behavior: there is the strongest, who fights and fights a lot, giving and taking, and in the end in most cases he is the one who manages to reproduce. On the other hand, there are all his “traveling companions” who try to rebel, but always succumb and are unable to reproduce.
Finally, however, there is also another male, the one who already existed on the site, he did not make the trip with the others: he looks at the struggles of others and throws himself in into the fray and deposits his seed. Often it is this individual who succeeds in fertilizing the eggs.