Aquarium of the Pacific - Online Learning Center - Species Print Sheet
Conservation Status: Safe for Now
Climate Change: Uncertain
Mudskippers in General
( )Bony Fishes, marine
There are 40 species of mudskippers divided into three broad types. The smallest leave the water only at low tide and stay at the water’s edge. Medium-sized mudskippers spread across the mud flats. Many are territorial building a low ridge around the boundary of their territory. The largest live at the highest part of the mud flat that is covered only at high tide. This type is known to eat small mudskippers.
At the Aquarium
Humans use a variety of products to treat dry skin. Our aquarists report that they have seen our medium-sized mudskippers treating their dry face or gills with water. When they feel the need, they dip a fin into the water and then wipe the dry area with the wet fin.
Indonesia, Africa, Indian Ocean
Mudskippers generally prefer mangroves, nipa palm areas, and tidal mudflats. Depending on the species, they may be found in freshwater, brackish, or marine areas including estuaries, swamps, marshes, and tidepools. Medium-sized and large males dig funnel-shaped burrows in the mud with their mouths, always keeping the entrances underwater. Small mudskippers do not build burrows.
Mudskippers are torpedo-shaped gobies. They have muscular, arm-like pectoral fins that function as legs when they are on land; two dorsal fins; and, depending on the species, their anal fins can be joined to form a sucker that aids in climbing. A muscular tail allows them to “skip” over land. Mudskippers also have lateral lines on their foreheads. Early in the larval life of these fish, their eyes migrate to the top of their head, where they are located close together. Internally, their protuberant eyes have cones above for color vision and rods below for monochromatic vision, allowing the fish to see both above and below water at the same time.
Coloration varies, but is normally a brownish mud-color that camouflages these fish in their natural habitats.
Size is species dependent and varies from 7 cm (2.75 in) to 25 cm (9.75 in)
These fish are carnivorous and eat a variety of small animals including insects, crustaceans, and worms. Part of the day, mudskippers sit motionless in the mud looking for insects to eat. They use their strong shoulder fins to chase insects across water into mud.
During mating season, male colors brighten and their chin and throat turn a bright gold color. Males display to females by doing push-ups with their pectoral fins and by leaping into the air, spreading their dorsal fins at the top of the leap before flopping back into the mud. The nesting burrows that some mudskippers build are funnel-shaped with a wall at the entrance to keep a pool of water over the top during low tides. If the acrobatics of a particular male impress a female, she will follow him back to his burrow. Fertilization is internal. The female lays her eggs on the roofs of special brooding chambers in the burrows. The male guards the nest.
Smaller species of mudskippers tend to reproduce near the shoreline, and release their eggs into the water. Medium and larger-sized species tend to reproduce on land, and either build a nest closer to the water which fills naturally with water or build burrows so as to have access to the water necessary for the survival of the eggs. The nest-guarding male keeps the eggs aerated by gulping air at the surface, descending into the burrow, and then releasing that air into the water containing the eggs.
Because water does not flow through their burrows, mudskippers’ homes are normally very low in oxygen. To overcome this, they repeatedly gulp oxygen and release it inside the burrow, oxygenating the water which then allows them to remain inside for up to 30 minutes at a time. This behavior also provides oxygen for any developing eggs.
To see above and below the water, mudskippers pop their movable eyes out of the water and move them up and down like a submarine periscope. Their eyes work independently of each other. When they swim, the fish keep their heads above water, using their aerial vision to give them a 360o view. When out of water, they periodically roll their eyes back into their sockets to keep them moist.
Mudskippers have adapted to an amphibious lifestyle so that they can shuttle back and forth from the water to land. Many of these fish actually spend 90% of their time on land! When in the water, they breathe with their gills as most fish do. Before climbing out onto land, these fish fill their over-sized gill chambers with water, creating an oxygen tank that allows them to breathe out of water. On land, these fish also moisten their gills periodically by wiping them with their fins. To get additional air, mudskippers can also breathe through their blood capillary-rich skin, and blood-rich membranes in the back of the mouth and throat. They often keep their tails in water and roll in puddles to keep their skin moist.
Mudskippers’ fins have adapted so they can walk, jump, swim, and climb. Their pectoral fins are used to move about on land where they don’t actually walk, but instead move in little hops by keeping their bodies rigid and jerking forward on their fins. This movement is called “crutching”. The pelvic fins of some species are joined together under the body to form a type of sucker that helps these fish creep up rocks and mangrove roots.
These fish live for above five years.
Their numbers are declining because of habitat destruction caused by human activities such as development, clearing of mangrove forests for shrimp aquaculture farms, etc. They are a human food item in some countries.
The mudskipper excavates its burrow by scooping out mud with its mouth and carrying each mouthful to the edge of its territory where it is spit out to create a wall which completely surrounds the burrow.