Also, fwiw, I usually start with detritivore kits from Inland Aquatics and Indo Pacific Sea Farms to get the little things that mean a lot and reproduce in the tank.
www.ipsf.com
www.inlandaquatics.com
I am NOT a fan of hermit crabs as they kill and eat snails, then steal their shells. Crabs in general are omnivores and may eat many beneficial critters.