I've seen a few bettas on AquaBid listed as such & such "devil". A few look very similar to my guy Colonel Potter. I'm assuming it's a color pattern, so what exactly is a "devil"? And is Colonel Potter one?
Black Orchid, Black Devil, Black Ice
Henry Yin first coined the name Black Orchid to describe his particular development of dark bicolor Crowntail, which was (so I've been told) NOT a marble-based black but a melano type with excessive steel iridescence, particularly in the fins. The name has since been applied to any fish of similar coloration in a multitude of forms, from HM to Plakat, but these almost always come from marble. Essentially, the Black Orchid betta is a dark black color with streaks of steel blue in the fins, often forming almost a butterfly pattern. The iridescence is not always limited to the fins, and many Black Orchids also develop red wash (another indicator of the marble gene messing with this line). Increasing the red wash has given a new type of 'black' - the so-called 'Black Devil', which is a marble type black with red in the fins instead of iridescence. They do not breed true, and the production of the Black Devil betta seems to be very much the luck of the draw. The Black Ice betta is also derived from marble, and can appear randomly in marble spawns. It is a black fish which varies in intensity and possesses generous iridescence in the body and the fins. The iridescence in the Black Ice fish can be either steel, royal, or green. Selective breeding has increased the percentage of Black Ice offspring from Black Ice pairings, but it still does not breed true.