Sexing my GT threads come up every couple weeks, because juvenile GTs are hard to sex. I currently have 4 male and 3 female breeding size GTs raised from my third generation fry. Young GTs have no external sex difference so there is no signature feature you can use to pick out the sex. At sexual maturity, which can be as small as 4 inch, females can turn darker showing a black beard on the chin, and accentuating two vertical white stripes on the body. Males do not turn dark and stay brightly colored at all time. But dominant females not in breeding dress can be as brightly colored as males. I was mistaken several females as males until one day they turned dark and dropped the egg tube. IME, juvenile GT males do not out grow females until they hit the 4 inch mark as I sort out the largest juvenile from the same batch thinking they would be majority males. Wrong, the sex ratio turned out to be about 50/50 as they matured. Once passing the 4 inch mark, sexing them get easier as males will begin to outgrow females, develop a steeper forehead, and outshines females in color.
The OP GT shows a black beard on the chin so it looks like a female, but it is still too small to tell as an unhappy male can look like a female.
