Mudskippers are fish that use their fins to walk and skip on the mud at low tide. They breathe through their skin and the surface of their mouth when out of the water but they must remain damp. They store water in their large gill chambers on their neck. They will fight other mudskippers over their territory.
When the tide comes in, they find protection from other fish by living in a burrow in the soft mud. Their burrow has a chimney built on top and they create an air pocket in the chamber below. The eyes on the top of their head allow them to swim with their eyes above the surface so they see predators from all directions.
See the mudskipper crawling in the mud