Picabo Angler

Pee-Ka-Boo is a Native American word meaning "Shining Waters."

Picabo Angler is a destination: A full-service fly shop & outfitter located on the banks of world-renowned Silver Creek

Distinguishing A Male From A Female Trout


As a guide, I am often amazed at the look of someone's face when I comment that the fish he or she has just caught is a male or a female. "How can I tell?" they immediately ask while examining the underside of the fish for an obvious visual cue. Below are a couple of images that explain the difference. Note, it is often more difficult to determine a trout's gender when it is still a juvenile, ie under 9 or so inches.

Here is a female Brown Trout caught recently on the Big Wood River below Magic Reservoir. Note the size of the jaw in relation to the size of the fish. Also important to note is the rounded shape of the jaw on a female trout. While hard to see in this image, the anal fin on a female Brown or Rainbow Trout will be slightly concave and a male's anal fin will be slightly convex. Looking at the jaw generally does the trick though and the short rounded jaw on a trout is the tell-tale sign of a female.

photo: john huber

Here's an example of a male Brown Trout. Note the elongated jaw and even the convex anal fin. Males also often have a slightly longer lower jaw. The jaw on the male brown is not short and rounded at all... An elongated jaw on male trout and male salmon as well is called a Kype. The older the male trout becomes, the more elongated Kype it will have. The above image was taken on Silver Creek.

photo: nick price