OK well im really happy with my tank right now but i need some fish that would hang out on the top of my tank. The tank is 20 gal at the moment the curent residesnts are as follows 8-10 Hermit Crabs, 2 Spider Decorator Crabs, 4-5 in Horseshoe crab, 1 Green brittle star, MediumToadstool Leather...