Male and female trout

[BigZee44]

I was wondering if there are any sure fire ways to tell if a rainbow is a male or a female.  I ask because i like to keep a fish or two one in a while to put up some eggs for bait but have a heck of a time determining wether some trout are male or female.  I know that most of the time a hen with eggs will be lighter color and have a more rounded nose and a male this time of year will be getting more color and begin to have a hooked jaw.  But i have been proven wrong a couple times lately.
For example the bigger trout was a male and i thought for sure it was a female.


I'm just looking for any feedback from anyone experience. thanks
Zack

[Icemanjim]

I've always wondered that myself, I do know that when they flop and you squeeze one a little too hard, the males let you what they are.

[Riverb8]

I'm with you BigZee,

I have a heck of a time telling them a part until I open them up. By then its too late.  Since I don't usually use the eggs for bait, I would like to be able to release the spawners. 

[4x4elk]

Little one a male and big one female! Ok I don't know really but looks like you had fun

[Dorado]

You can tell with trout.....sometimes. 

With  most salmonids that have never spawned or matured (like the ones in the pics) it is impossible.  Females get a more "rounded" head, and often have a distinctive bulging look to their bellies when they are full of eggs.  Males that are preparing to spawn or have spawned several times will develop a kype or hooked lower jaw, and sometimes have brighter coloration. 

Generally, if the fish has a "short" looking lower jaw and a rounded head it is female.  Take a look at the big Laker posted by BD a few weeks back in the Wyoming Hardwater hotspots, you can see the rounded shape to the head and jaw of a female. 

When you look at enough of them side by side you can tell...sometimes!

[BigZee44]

I definatly agree that it has to do with maturity.  Older fish have more distinct characterists. 

[4cator]

Interesting rainbows you have there. When I first looked at them I thought that they were stockers. Then I noticed the adipose fin. I cannot see if they have much of a dorsal fin. Did they have a full dorsal??  Fat and healthy buggers I must say. 

[vermonner]

The females are the ones that will second guess anything that you are doing...
They often ask "are you sure?..."