I wasn't able to sex mine until they spawned, and then once the breeding tubes were down it was easy (typical too: males, small pointy. Females, large & blunt).
Later, as they matured beyond just being able to spawn the Male got noticeably bigger, thicker, and had a steeper forehead. I wouldn't go so far as to call it a nuchal hump, but it was different when seen next to the females.
Also, that old adage about males getting longer pointier dorsal and anal fins? That was true - but for the longest time both sexes had trailers that extended to the back edge of the caudal fin, or close to it. However, as the male matured his trailers got even longer.
They extended past the caudal fin and this part is going to be hard to describe but the trailers on the dorsal fin kind of curled down a bit, and then extended past the caudal fin, and the anal fin trailer kind of curled up and then extended past the caudal fin...
It was almost as if the trailers grew closer together and THEN started shooting straight out past the caudal fin on my old male.
Again, hard to describe but easy to notice when you see it. I'll see if I can find an old photo (it's on an older computer that may or may not work)
