It's been about ten years since I lived in Casper. If I remember right the only decent pet store was in Sunrise Shopping Center, and it was just slightly above WalMart in quality.
You won't find a better plant store than The Planted Tank Swap and Shop section.
Wow that brings back some memories. I left casper in 98 and used to go there when I was a kid. Sounds like somebody in casper needs to take another shot at opening an lfs there. If only the chains are in town people get tired of the poor selection and then start looking for a more specialized shop. Well at least thats how it is in Anchorage..which is why the shop I work at is doing so awesome.