Petsmart usually has a couple. Not the best quality, I know, but they are only a buck and from what I have seen (I looked around for otos about six months ago as well) they are the only place in GB that has them. Maybe all Reefs? They have some FW fish and could have some.
funny you should post. I dragged my family down to oshkosh today to go see aquatic pets. The wife was shopping at the outles, and I a grand time just poking around without a time limit. Everyone was super nice to my son and I.
I ended up leaving with my otos as planned, but I ended up buying about 15 more items. Totally worth the trip. Prices where pretty good also.
In the future I will check. I just have not had luck with pet chain fish