When getting babies it’s nearly impossible to tell the sex until they are 2-3 inches big. Fortunately Bn are quite common and getting a sexed one isn’t too difficult.
you could try getting a picture of the babies top view, sometimes males will show a thicker head when young and sometimes not. It can vary from all the different growing conditions. I once had a few batches that were very heavy in females as some people reported backto me asking what the hell and how they ended up with all females when they took 5-8fish each. I still have no answer for them lol
it will always be a gamble with fry