Sexing blue acara?

[Packers1993]

So I've had this acara for 3 months now and I for sure thought he was a male but after doing some research I'm not totally sure?

 

[Fishies4Ever]

I am thinking it’s a male because of its longer more pointy fins. Males can also have a slight bump on their forehead and it gets bigger as they get older. I am not sure though, is there a specific reason you need to know if it is a male or female?