The water is cloudy. Check the ammonia, nitrite, nitrate.
Too young to sex it. if you want a breeding pair of cichlids, buy 8-10 young fish and grow them up together. When they mature they will pair off naturally and you can move the prs into their own tanks, or keep a pr and remove the others.
As a general rule, male blue acaras get longer more pointed dorsal and anal fins when they mature. females have shorter more rounded fins. Electric blue acaras are more inbred and don't always have the same quality fins so you might get males with shorter fins.