I'm thinking of getting a mate for my female GT, can I tell what sex they are at the fish store when they are small? And if so how?
I found the best way is to look at the dorsal fin, The back will be more pointed on the Male. Females will also have a slightly pointed fin later but it takes years. I also found domanant Males tend to have the more of a point and more color than others of the same age and size. look for these characteristics in the biggest of the fish at the store, they are usually Male.