There is not only one or two genes that make a betta halfmoon. I believed there are many , may be 10 or may be 100 genes involved to make a betta a halfmoon. I call those genes “Multiple Genes”
   This is my assumptions:
-Gene that make rays straight,
-Gene that control rays branching to 4, 8 or 16,
-Gene that make caudal spread to 180 degree,
-Gene that make all the finnage big and strong,
   If one or two genes fail to get to their offsprings, then the offsprings are not halfmoon but only Super Delta or Delta.
   We must have every genes that make a betta halfmoon to go to their offsprings and not only some of the offsprings, it must be all of them. Imagine, how can you throw a hand full of powder into a tray. No way. The only way to do is to bind them togather. Therefore, we need to find out what is the binder for all these genes. Until then we can have 100 per cent halfmoon in a spawn.
   Irridescent means blue, turquoise and steel blue. They are in dark color catagory.