I disagree. There has been some good anecdotal information for the OP, who raised the very questions of both gender and kok size. The info we have given is certainly more helpful to OP than "throwing in spanners" and suggesting his fish, which was sold to him as a male from a "reputable seller", is a female, then trying to back it up with some weird explanation that nobody else, incl. I'm sure the reputable seller, has ever heard of. For you to suggest there is no correlation between kok size and gender with ZZ's is what isn't helping OP at all.