You can locate information of spawning practices on various websites, but what i can remember the male creates a circular nest on the lake bottom by uprooting plants and creating a "bed". The female lays eggs and the male fertilizes them while protecting the fry until they are old enough.
as far as sexing them... I was under the impression that the male Bowfin has more coloration then the female which is usualy more neutral in color (more brown than coloration).
Do you have many? If you are interested in selling/trading one i would love to find one which is around 6". PM me if you want to, or if you know where to easily locate one i would be thankful.
Oh and BTW itsbadlands, they arn't like a snakehead, other than some similarity in body type. They are a prehistoric species which dwells predominantly on lake bottoms. However they are aggressive as they are predetory fish. they are not as aggressive as snakeheads are when it comes to just killing other fish