I got some opaque in my collections , so just wanna share some info's about this type ,down there is an article about opaque types taken from ; www.bettaterritory.nl
Opaques were created by Dr. Gene Lucas. To be correct opaque itself isn't a color but a trait which is characterized by a thick powdery appearance. The opaque (Op) factor is inherited by intermediate (partial) dominance.
Opaque does not necessarily mean white, there are actually three types; steel blue, green and blue (royal blue) opaques. Opaque whites are actually steel blue opaques. Green and blue opaques have a green or blue sheen instead of pure white colour.
The genetic make up of a opaque white is represented by: C bl Si Nr Op .
C - The cambodian gene for lack of dark body pigment which causes the light body.
bl - Steel blue pigment which appears silvery-white when on a light background.
Si - The spread of the iridocyte pigment, in this case steel blue over the fish.
Nr - Non-red, causes the inability to produce red pigment.
Op - Opaque, the special gene that cause the powdery appearence of the fish.
Note: It is also possible for opaques to arise as a result of marble genes. In order for that to happen off course the steel iridescence and the opaque factor must be present.
The I.B.C. judging standards define this breed (Opaques) as: Non-Red light bodied fish similiar in appearance to Pastels. However, there are guanine deposits giving a denser milkier appearance and an opacity to the coloration of these fish. These deposits are most visible around the head and eye and continue to accumulate as the betta ages.