While they might end up in a LFS from time to time, mislabled and unrecognised by an ignorant staff, due to the way they have things set up with their wholesalers and disributers, I don't think there's ANY way, EVER, that true zebras would have any chance of making it into a Petsmart or Petco. They order in advance, automated, in bulk, from regional distributers (some exclusive to them) and they order common, cheap, high-volume-sales fish and almost never the expensive, exclusive exotics. They won't take any stock from any local private breeders.
All of their stock is wild-caught or mass-bred on giant farms. If the fish were farmed, the breeders would know WHAT they had. If they were wild-caught, the chances that the collecters, the transshippers, the wholesaler, AND the individual store would ALL have zebras pass through their hands without recognising them is very, very close to zero.