My LFS have a few really knowledgeable staff. Both Petsmart & Petco didn't seem thrilled with glowfish. Seems they do tend to have shorter life spans, but not clear if it is due to the genetics directly or a bad shipment or if they are simply more sensitive to living condition and die as a result of poor care.
Anyway, point is, both stores steered me away from them as good fish.
I've read that zebra danios are not good tank mates for betta and the Petsmart girl agreed. But maybe the glowfish are a bit more docile??? Cause she thought they were a better fit for a betta than the zebras.