We just like to keep the original lines of morphs as pure as possible. While the D. auratus are not particularly threatened or endangered at this time, we still like to keep things more or less "as they were," perpetuate their original blood lines and DNA. I don't know anyone in the hobby of keeping and breeding darts seriously that is into creating "designer" frogs from the species that one day may exist only in the hobby, due to habitat destruction and whatever else the politics of exploitation vs ecology involves. It's not as if we are breeding and keeping them to eventually repopulate their depopulated (and eventually non-existent) rainforests. That won't happen. We are keeping the captive bred animals of original imports as close to the originals as possible. It's more of an ethical problem that even those of us who believe in this, can't totally explain.
There's nothing to keep you from mixing blues and greens, or whatever you want. There's no law against it, and I'm not sure it will matter in the long run. Just don't misrepresent any of the offspring as anything but hybrids if you either sell or give them away-- on the off-chance you even get any. In the meantime, just enjoy them.
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Patty
Pahsimeroi, Idaho
4 D. auratus blue
5 D. galactonotus pumpkin orange splash back
5 D. imitator
6 D. leucomelas
4 D. pumilio Bastimentos
4 D. fantasticus
4 P. terribilis
4 D. reticulatus
4 D. castaneoticus
2 D. azureus
4 P vittatus