How big is your tank? Is it tall or shallow?
I have a purple firefish that doesn't hide and a six line wrasse that is all over the place. I have heard six lines prefer swimming up and down, so that is why I asked about tall or shallow. Have you considered clowns? They are usually the go to nano fish.
How long is your tank up and running?
I think you should wait a month or more before adding any more fish (even then only add 1, then wait another month or three, then add hour last fish).
I am a sucker for pairs. Why not find mates for your two fish. I think a black ice would be a cool compliment to your picasso (make sure you find a proper mate though, in regards to size and sex).
A picture of your tank would help, as aquascaping/layout & sandbed is a factor.