Melanistic Trout?

[Eccles]

Ah no. Sharp eyed JackM. Intraspecific I should have written. Thngs like dominant fish having bolder colours, submissive body darkening by ousted fish following aggressive interactions, even eye colour is used to sort out hierarchies.
Interspecific communication does occur but is less documented. Cleaner fish advertising their wares, possibly the way billfish 'light up' that sort of thing. I sometimes get the feeling that panfish like bluegills can change colour really quick. They come to hand dressed in that coral reef garb but have dulled by the time the get returned. Don't know if it is my imagination but it seems v. rapid.

 

[JackM]

Not a sharp eye at all, I was poking fun at the fact that no one probably understood most of your explanation, particularly when it appears that fish can communicate interspecifically with regard to skin tone. But now I see that you mean their skin tone may change as a means of communication, which makes a little more sense.

 

[PACOFRANSICO]

Yeah I know its a brookie i was just lookin though the old pics and found that really dark brookie. It was caught late fall so thats prob. would explain the coloration.