Can't figure out if your GF is a male or female? Well lets see what we can do to help you.
Sexing GF can be a challenging job no doubt, but can be done. Spring is usually the best time of the year to sex them, although it's possible to achieve your curious wonders anytime.
Females usually have whats called a
Convex vent (anal opening). This means the vent protrudes out some, kinda making it look swollen. Females will also seem more rounder on one side, as they are probably carrying eggs. Females will also have a nice smooth pectoral fin and may seem wider.
Female:
© aquapuppies.comMales on the other hand are much easier to sex due to them getting beautiful breeding stars known as Breeding Tubercles on their pectoral fins and gill plates during spawning season. This may look like Ich but isn't.
Breeding Stars:
© aquapuppies.comThe males vent will look
Concave meaning it's inwards more. Their vent will be harder to see in other words. All you may see is a tiny little bump on his rump

Also males will chase the females (see "Breeding Behaivor")
Male:
© aquapuppies.com