these fish are hard to sex just by looking at one fish, IMHO if you had several of them in the same tank all over 7 inches the males tend to be longer and leaner body profile and the females seem to be shorter and plumper around their girth. If you do a search in the past you may find some of my older posts that show my "school of argentea's" in a 180. My largest male is closing on 12 inches and the females are at the 9 inch mark.