I read somewhere that you can tell the sex of a LMB by the shape of the scales around the vent. Is there any truth about this?
Im not a fish biologist or a pro but. When in spawn the males stay on the nest to fan and protect. Not sure but usually no deeper than 24" of water so u can see them when the water is clear. I know everyone probably knows this.
I had a LMB as a pet that i got off of the stock truck. I did this to observe the behavior of "him". I know his sex because at about 13" he started making a nest in the bottom of the aquarium and became very agressive even towards me, when I cleaned the tank.
Only way to 100 percent accurately sex a fish is by use of a capillary tube around spawning time -- Or the expellsion of sex products by gentle squeezing.
The capillary tube in probed into the urogenital oriface and tilted back and to the side. However, if not done correctly you can injure the fish. The presence of eggs in the tube is a dead ringer. All other methods are not 100 percent.