The tinge of blue on the head in the first pic makes me think male, though females will get a bit of blue and a lot of dull yellow along the flanks when they fully mature. At that small size, the blue makes me think male.
These guys, as well as the sulfur-headed variety are some of the only Protomelas that actually live towards the top of the water in the wave-washed rocky habitat. Most other large Protomelas are open-water fish. The spilonotus eat mostly small insects that fall into or sit on the top of the water.
