hahah I love that! I have a 'George' who also may be a girl
I'm not sure if these are actually classified as sharks, but sharks usually have claspers near the analfin in males and they are absent in females- this goes for sharks like dogfish, mako, great white ect. ect. so I'm not sure if this rule applies to these little guys but you could do some research on that!
These are a type of minnow. Generally it’s tough to tell male/female but most males have black on the analfin in front of the tail. I’d say yours is male.