The Blue Layer in Betta Splendens The blue, or iridescent, layer sits on top of all other color layers and produces structural color through light-reflecting crystals rather than pigment. In normal bettas, this iridescence appears in limited areas, but genes like Spread Iridescence, Mask, and Metallic can increase its coverage and intensity. Additional genes such as Dragonscale and Opaque modify the layer further by thickening scales or adding a milky coating, sometimes affecting the eyes. The specific shade of blue is controlled by partially dominant blue alleles. Since these are on the top layer, they are difficult to remove once introduced into a line. #genetics #learn #bettabreeding #bettatok #fishtok #wickedbettas #STEM