perhaps the # of yellow dots, or that his dorsal fins arent pointy at the end. however it could just mean that sometime before another fish nibbed his fin. but I m not so sure I still say its a girl.
The only trustworthy way to tell what the fish is is to catch it and look at its venting. A female has the back hole clearly bigger than the front. The males two are the same size. If the fish is 2-3 yrs old then this will be clear. Catch it and turn it over. Stop all the guessing.
I have done quite a number and can now sex a fish that is about 3cm long withouit too much hassle.