Pond Boss Forums INTRO Questions & Observations Bluegill sexing

Normally when dealing with good growing BG the smaller they are than 8" the less accurate the method becomes. However slower growing BG can develop the typical external sex characteristics at 4"-5". This happens most often when they are stunted or living in far south waters. With rapidly growing BG and a good dominance of mature males in the BG population, the young males do not become fully mature until 7.5"-8". NOTE: This becomes less of a rule as one goes from North to South. 'Southern' BG have shown they can develop grow to maturity at 1-1.5 yrs old. I assume this most often occurs in ponds where there are not a lot of large Bull male BG.

The very best way to accurately sex BG is to learn to probe the urogenital opening using a capillary tube. Sex check verification of fish with a capillary tube that is carefully pushed into the urogenital opening during spawning, but if you don't know what you are doing you can damage the fish.

The easiest way is to sort male vs female of most species of fish is during spawning season. The males will expel milt with some abdominal pressure while the females will be either really distened with eggs, or if they have recently passed the eggs and their bellies will be as flat as a quarter. Plus the urogenital area is redended, sometimes noticeably so. But even if a fish has a distended belly it is imperative you check for milt.