Odds are you actually have only one species. Betta Splendens is the only one commonly seen in stores, with assorted subvarieties like half moon and veil tail. Any of these varieties can successfully interbreed. If you are dealing with another species of betta, they may be able to breed, but the offspring (if any) will almost certainly be sterile. speciation is actually determined by the ability to breed together. Any of the varieties of splendens will breed together just fine tho.
