Mudskippers are able to breathe out of water by retaining water in their gill cavities and refreshing it as necessary. It is also thought that like amphibians, some species are able to absorb oxygen through their skin.
Perhaps the most unusual and striking of mangrove fish are the mudskippers. These fish are closely related to gobies, and somewhat resemble them, with their bulbous eyes and modified pectoral fins, which allow them to traverse the mud as if walking.
Ironically for fish, Mudskippers spend most of their time out of the water where they breathe with the water trapped in their gill chambers. They absorb oxygen with special blood vessels inside their mouth and through their thin skin.
Occasionally they dip into the water-filled holes to wet their gills and scaleless skin, while their eyes can be individually rolled back into their head to regain moisture.
Furthermore interesting species such as the Gold-spotted Mudskipper exist, which will not crawl across the mud with their modified fins, but actually use them to haul themselves up the roots and trunks of trees.