I would say put a flat stone or something in the tank and just wait and see if any eggs are laid. I had a female FH for a little over a year. It was a gift to me as a baby, and it took about 7months before I was able to postively know she was female. For the longest time everyone kept saying male, because she had a bigger head. Then one day she got fat and super red around her gills. She started laying eggs about 7 months old and continuously did it about every 3-4wks. She always exhibited the same aggressive behavior and color change right before. She would also get darker afterwards and get the dark bands around her body. She also had the flowering marks up in to her dorsal. Hope this helps.
Great looking fish by the way. Looks like my old one. Miss her!
