I had a GT that I couldnt tell until it was about 6" or so, then he started to develop a hump. IME nuchal humps arent a reliable way to id a lot of cichlids, some females may have a forehead that is larger than some males that are supposed to develop a hump. The pics didnt show on my computer so I cant help, I'm just saying IME humps may not be something you want to bank on