Red head goby and the green banded goby are very tiny gobies that seemly have no fear. They'll be the first to dart at the food, when you are cleaning, they seem to allow your hands to get very close before swimming away unlike some fishes that is in hiding as soon as the lid is opened. Durable as hell too, great for the nano, may easily get lost in a large tank but having a group on the bottom is pretty cool.