Well, I'm no biologist but it has always been my assumption that the fish received some sort of damage to it's nose when it was young. I have caught some planted trout that have had similar noses although not nearly as extreme looking more blunted and not turned down. I have caught them early in the year when their noses were still raw from the rearing pens and then later in the year they seemed to heal like that. I don't know if this is the case but just my observation.