Aquarium Tunnel Shelter Tube, Fish Shrimp Cave Hideout for Aquariums, Acrylic Fish Viewing Tunnel, Shrimp Habitat Tube -White 7.8″ X 1.8″ X 1″. Aquarium Tunnel Shelter Tube, Fish Shrimp Cave Hideout for Aquariums, Acrylic Fish Tube Viewing Tunnel, Fish Shrimp Habitat Tube -White 7.8″ X 1.8″ X 1″.