You have Dan’s Fish in Casper. I have received a couple orders from him that were mislabeled both times but good stock.I'm in Wyoming, population of under 60k so petco and petsmart for me. All my shopping is online or 5 hours one way to go to Colorado. When I lived in bigger cities, there was usually 1 or 2 good ones within an hour drive.
Fish and exotics are just a small segment of the pet industry. Even places with a large population can have trouble supporting quality stores. People can easily buy everyday items like food or chemicals online or at a closer chain store rather than supporting a quality store if they have to drive that far
I have 2 that I regularly visit and 3-4 more in the Seattle limits I could. Aquarium Coop is about an hour away. The Wet Spot is 2.5hrs.