Perhaps I'm not fully understanding your question. All of the trout appear to be brown trout. Even though brown and brook trout spawn in the fall hybridization between the two is extremely rare in the wild. Such crosses (most commonly the result of egg and milt manipulation in the hatchery) result in the so-called "tiger trout" which has a very distinctive marking pattern (usually described as "reticulated" or net-like), and being a cross between a trout (of the genus Salmo) and a char (of the genus Salvelinus), is sterile.
Coloration in salmonids can vary quite a bit, frequently in response to habitat conditions.
Coloration in salmonids can vary quite a bit, frequently in response to habitat conditions.