Often times, trout fishing guides will refer to a fish as either “he” or “she.” It is highly common for our customers to ask, “how do you know the sex of the fish?” We’re posting a couple images that may help you identify the sex of the fish you have caught.
Although it is very hard to identify the sex of a juvenile trout, adults (of all salmonids) display characteristics that make identification rather easy.
The image above is of a female rainbow trout (Oncorhynchus mykiss). Females typically have a rounded, softer “nose” or “snout” and typically have a smaller mouth.
The above image is of a male rainbow trout. The nose of the fish is much pointier and has a larger mouth. Also, the fish’s lower jaw has developed a “kipe” or a hooked lower jaw. Little is known as to the function of this feature. But, it is helpful in identifying the sex of the salmonid (pronounced [Sal-Mon-Id] or [ˈsælmənɪd]).
The color variations of the above illustrations are seasonal. The female pictured above has typical rainbow trout coloration for most of the year. Whereas the male displayed is colored more vibrantly which is characteristic of what a rainbow would look like during the spawn, which happens naturally in the Spring.