Do you mean breed different varieties together? If so, yes they're all the same species, but don't forget you will be producing 'mongrel' fry.
Breeders put a lot of time and effort getting groups of genes together to produce the varieties, so you'll get a mixture in crossbred fry. Even though they might look, outwardly, like a proper breed (as some mongrel dogs look like pedigree dogs) they will be crosses, and you won't know what any fry will look like.
You're also likely to lose some of the colours and patterns altogether, as some colours (like red) are more dominant than other colours (like blue).