The irridescense is mostly just seen because of the flash of the camera. Just looking into the tank, I see a dark silver body with the black dots/lines and red fins. I'll see if I can take a pic further out.
I paid $10/each for them. They could have been $7.50 for smaller ones. These are pretty big already. They are supposed to reach a max of 3" and they are pretty close to that now. They are considered a dwarf rainbow.
I wanted a shoal of Boesmani, but everyone said they need a 4' tank. Mine is 54 gallons, but it's a corner tank.
54g Corner Bowfront Planted, 2x24w T5HO
220g Mixed Reef