Opalines, golds, gold opalines, three-spots, blues, cosby, platinum etc are all exactly the same species - trichogaster trichopterus. The only difference is in color. The 'sumatranus' is simply used to describe the fish as a sub-species though actualy it is just a color morph. It's similar to the leopard and zebra danios which are given slightly different scientific names but are exactly the same species - just a different color morph. On the other hand there are fish like badis badis badis, badis badis siamensis and badis badis burmanicus which belong to the same genus and species but belong to rather different subspecies.