@flagg37 Assuming you're wanting saltwater livestock, I believe the closest LFS would be About Fish in Westminster. I love the place. You can tell they take good care of their fish, they usually have a good selection, and are competitively priced. They also sell coral, but if that's what you're going for, the best (and closest) pieces will be at Elite Reef in north Denver; I value their knowledge base the most. Liquid Kingdom in Broomfield has a good selection of fish and some coral, but generally a little bit pricier; friendly staff though. If you feel like going into Boulder, hit up Exotic Aquatics. Great staff and decent selection of fish and inverts. Don't bother with Aqua Imports (they treat their fish like crap and most everything is overpriced).
Have fun exploring the area and welcome! PM me if you ever have any interest in frag swapping