The fin length varies with strain. My male has trailing dorsal fin that touches the tail. Comparing your male with mine, your male looks like a female. I have seen male GT in the web that has trailing fin an inch longer than the tail.
However, within the same batch, fin length is a good indicator for sex, provided that fighting don't prune the fins. Next time when I have another batch of GT, I will check what size I can start sexing by fin length.
However, within the same batch, fin length is a good indicator for sex, provided that fighting don't prune the fins. Next time when I have another batch of GT, I will check what size I can start sexing by fin length.