Where Are Mudskippers Found and What Habitats Do They Need?

Mudskippers live along tropical and subtropical coastlines from West Africa through the Indian Ocean to Southeast Asia, Australia, and the western Pacific, with their greatest diversity concentrated in the Indo-Pacific region. They occupy the narrow, dynamic strip where land meets sea: mangrove forests, tidal mudflats, estuaries, and occasionally the banks of freshwater rivers. What makes their habitat requirements unusual is not simply that they need water or land, but that they need both simultaneously, along with specific sediment types, tolerable salinity ranges, and enough soft substrate to excavate the elaborate burrows central to their survival and reproduction.

Global Range and Regional Hotspots

Mudskippers belong to the goby subfamily Oxudercinae and include roughly 40 recognized species spread across multiple genera. The family’s range sweeps across the tropical and subtropical Old World. You can find species along the coasts of West Africa, around the Arabian Peninsula and Persian Gulf, throughout the Indian subcontinent, across Southeast Asia, into southern China and Japan, and down through Indonesia, Papua New Guinea, and northern Australia. A few species reach as far east as some Pacific island groups. Southeast Asia, particularly the coasts of Vietnam, Malaysia, Thailand, Indonesia, and the Philippines, supports the highest species richness.

Within that broad distribution, different genera and species carve out distinct ecological niches. An exploratory analysis of habitat conditions across the subfamily identified five ecological guilds distinguished by the amount of environmental water available and three additional groupings tied to different salinity levels, with a partial match between these ecological categories and phylogenetic relationships suggesting parallel adaptive radiations within separate genera.¹ In plain terms, mudskipper species are not interchangeable in where they live. Some are highly terrestrial and spend most of low tide walking around on exposed mud. Others remain close to the waterline or stay mostly submerged, poking out only briefly. Where you find which type depends on the local combination of water, sediment, and salinity.

Mangroves, Mudflats, and Estuaries

The habitats mudskippers depend on share a common feature: they are intertidal or supratidal zones where the boundary between water and air shifts with the tides. Mangrove forests are a core habitat for many species. Mudskippers play important roles in structuring the communities of small organisms living in and on mangrove sediment, functioning as ecosystem engineers that reshape the mudflat surface through their burrowing and feeding.² They graze on algal films, consume small invertebrates, and turn over sediment, making them both predators and habitat modifiers within mangrove ecosystems.

Tidal mudflats without mangrove cover also support large populations, especially of the more terrestrial genera like Periophthalmus and Periophthalmodon. These flat expanses of exposed mud during low tide are where you will see the stereotypical mudskipper behavior: fish skipping, climbing, and squabbling over territory in the open air. Estuaries and the brackish lower reaches of rivers round out the habitat picture. A few species have even pushed into fully freshwater environments, a rarity among mudskippers. Researchers documented one species, Periophthalmodon septemradiatus, colonizing the banks of the Mekong River’s major channels, feeding and courting out of water and spawning in burrows excavated in the riverbank, across a range stretching from saline estuarine islands all the way to completely freshwater upstream habitats. Only two mudskipper species have been recorded from freshwater environments, making this an exceptional rather than typical pattern.

Field surveys from sites in South Sulawesi, Indonesia, found two mudskipper species inhabiting mangrove areas with water temperatures of 28 to 33 degrees Celsius, dissolved oxygen from about 2 to nearly 7 milligrams per liter, pH between roughly 6.5 and 7.1, and low salinity values around 1.7 to 2.6 parts per thousand.³ Those numbers give a snapshot of the warm, somewhat oxygen-poor, near-neutral-pH conditions typical of the muddy coastal waters these fish call home.

Why the Mud Itself Matters

Not just any shoreline sediment will do. Mudskippers need to dig, and different sediment types support burrowing to different degrees. When early juveniles of one species, Boleophthalmus pectinirostris, were offered a choice between medium sand, fine sand, muddy sand, and sandy mud, they clearly preferred sandy mud. The researchers concluded that while temperature and salinity probably set the large-scale boundaries on where mudskippers can survive, sediment type is the critical factor for determining exactly where on a coastline they actually settle.⁴

This makes intuitive sense once you understand what mudskippers do underground. Their burrows are not simple holes. They are branching tunnel systems that can extend tens of centimeters deep, with dedicated chambers for different functions. Fine-grained, cohesive sediment holds its shape and allows the fish to maintain these intricate structures without the walls collapsing. Coarse sand drains too quickly and crumbles. The preference for muddy substrates is not cosmetic; it is structural engineering.

Temperature and Salinity Tolerances

Mudskippers live in some of the most thermally variable environments on Earth. An exposed tropical mudflat at midday can push air temperatures above 40 degrees Celsius, while the same location on a winter night might drop to 10. Mudskippers cope with this partly by being physiologically tolerant and partly through behavior. Studies of two common species in Kuwait Bay found that their body temperatures across the year ranged from about 14 to 35 degrees Celsius, substantially narrower than the ambient air temperature range of 10 to 42 degrees. In winter, they avoid cold surface temperatures by staying in their burrows, then bask after emerging until their bodies warm above roughly 14 degrees before venturing onto the mud. In summer, they keep their body temperatures below the air temperature by choosing spots where evaporative cooling from wet mud can drop the effective temperature by as much as 7 degrees compared to the shade air temperature.⁵

Laboratory thermal tolerance experiments confirmed these patterns with more precision. Two Periophthalmus species both had an upper chronic limit of 37 degrees Celsius. Their low chronic temperatures differed somewhat, at 14 and about 11 degrees respectively, giving them acclimation scopes of roughly 23 to 26 degrees, which is a remarkably wide thermal window for any fish.⁶

Salinity tolerance is similarly broad. Mudskippers as a group are euryhaline, meaning they can handle a wide range of salt concentrations. One species from the Mekong Delta, Pseudapocryptes elongatus, survived salinities from pure freshwater all the way to 50 parts per thousand in a 96-hour trial, well above typical ocean salinity of around 35 parts per thousand.⁷ Not all species match that extreme range, but the capacity to handle fluctuating salinity is essential for life in estuaries and tidal zones, where a rainstorm can slash salinity in hours and an ebbing tide can concentrate it rapidly in shallow pools. Research has shown that maintaining stable salinity conditions is important for mudskipper health, with salinity fluctuations affecting blood chemistry and behavior.⁸

The Burrow as Life-Support System

If you had to pick the single most important habitat feature for mudskippers, it would be the burrow. These underground structures serve as refuges from predators, shelters from extreme heat and cold, breeding chambers, and, perhaps most remarkably, controlled respiratory environments. Mudskippers do not just retreat underwater when the tide comes in. Many species seal themselves inside burrows and breathe from a pocket of air they stashed there during low tide.

One species, Scartelaos histophorus, was observed depositing gulps of surface air into its burrow at an average rate of about 12 trips per hour during low tide. When researchers experimentally removed this air pocket, the fish replaced it in 97 percent of tests. While confined to its burrow during high tide, the fish breathed both from the water and from the stored air. As the oxygen in the burrow water declined, the air pocket became increasingly important. When the oxygen tension of the water dropped below a threshold of roughly 4.8 kilopascals, the fish switched almost entirely to air-phase breathing. The fish also monitored the quality of its stored air, expelling and replacing it when researchers experimentally reduced the oxygen content by mixing in nitrogen.⁹

In Boleophthalmus pectinirostris, air was found stored in 90 percent of burrows during summer breeding months but only 50 percent during winter. The volume of recovered gas ranged from 30 to more than 400 milliliters per burrow. Interestingly, adult fish proved able to survive total submersion in severely oxygen-depleted water for 8 hours, but no embryos survived to hatch under those same conditions. The stored air turns out to be less critical for adult survival than for the eggs developing in the burrow’s egg chamber, which cannot tolerate the low-oxygen mud environment without a supplemental air supply.¹⁰

How Reproduction Ties to Habitat

Mudskipper reproduction is tightly coupled to both the burrow and the tidal cycle in ways that would be impossible in a different habitat. The Japanese mudskipper Periophthalmus modestus deposits its eggs on the walls of an air-filled chamber deep inside the burrow. The male guards the burrow and, during each low tide, ferries fresh mouthfuls of air down into the egg chamber to keep oxygen levels sufficient for the developing embryos. If the egg chamber becomes hypoxic, the male increases his air-delivery rate.

When the eggs are ready to hatch, the male does something surprising: on a nocturnal rising tide, he removes the air from the egg chamber and releases it outside the burrow. This floods the chamber with water, and the sudden immersion triggers hatching. The larvae wash out into the rising tide. This entire strategy depends on soft, burrowing-grade sediment, tidal fluctuation, and a male capable of sensing oxygen levels, managing gas exchange, and synchronizing everything with the lunar tidal cycle.¹¹ A coastline with the wrong sediment, insufficient tidal range, or too much disturbance simply cannot support this reproductive strategy.

Adaptations That Define Where They Can Live

The habitats mudskippers occupy would kill most fish, and the suite of adaptations that lets them thrive on land also constrains where they can go. Their skin, for instance, serves as a supplementary breathing organ. The epidermis of Periophthalmus magnuspinnatus has extensive networks of blood capillaries running just beneath the surface, with a diffusion distance between the capillaries and the skin surface of only about 1.5 micrometers. This ultra-thin barrier allows gas exchange directly through the skin when the fish is out of water, but it also means the skin must stay moist. Dry air or prolonged sun exposure without access to water or wet mud would be fatal.¹²

Their pectoral fins are built differently from those of fully aquatic gobies. Mudskipper species that spend more time on land have pectoral bones that are significantly longer and wider than those of their more aquatic relatives, with reinforced shoulder-pelvic joints and thickened fin rays that support a distinctive crutching gait on land.¹³ Detailed imaging of the barred mudskipper’s fins revealed increased muscle complexity, specialized structures for fin extension, and skeletal modifications that allow the fins to function almost like primitive limbs, generating enough force to overcome gravity on land.¹⁴ These fins work well on wet mud and mangrove roots but would be inefficient on hard, dry, or rocky terrain, further limiting habitat options.

Vision is another area where mudskipper biology reflects habitat demands. Most fish are essentially nearsighted in air, but mudskippers have good aerial vision, which they use to spot predators and prey on exposed mudflats. Genomic analysis of two species revealed that mudskippers have lost one class of ultraviolet-sensitive visual pigment, likely because increased exposure to ultraviolet light on land made it a liability rather than an asset. At the same time, they have evolved a broader range of color sensitivity in their long-wavelength visual pigments, comparable in range to human color vision.¹⁵ Behavioral studies confirmed that the mudskipper Periophthalmus modestus uses a specialized retinal area tuned for horizontal sight on flat mudflats, rotating its eyes and lifting its head to aim at targets before leaping to attack, an adaptation that only makes sense in the open, flat terrain of a tidal mudflat.¹⁶

Feeding Rhythms Tied to the Tides

How mudskippers forage also reflects how deeply tied they are to tidal habitats. In a Kenyan mangrove, Periophthalmus sobrinus showed a clear tidal rhythm in its feeding activity, with peaks around low tide during spring tides and around high tide during neap tides. The researchers concluded that foraging activity tracks the shifting spatial and temporal distribution of prey caused by the combined effects of spring-neap tidal cycles, daily tidal timing, and day-night cycles.¹⁷ A mudskipper dropped onto a beach or a pond would not just be in the wrong place physically but would be out of sync with the environmental rhythm its entire foraging strategy depends on.

Threats to Mudskipper Habitat

The intertidal habitats mudskippers need are among the most threatened ecosystems on Earth. Mangrove forests have been cleared at alarming rates for decades to make way for shrimp aquaculture, coastal development, and agriculture. Mudflats are filled, paved, or polluted. Estuaries are dammed, dredged, and diverted. Because mudskippers cannot simply retreat to deeper water or move inland, habitat destruction hits them directly.

Pollution is a specific and measurable threat. In the mudflat region of southern Iraq, where oil industry activity is intense, researchers analyzed hydrocarbon accumulation in mudskipper tissues. They found ratios of specific polycyclic aromatic hydrocarbons consistent with both petroleum input and combustion sources, confirming that these fish accumulate pollutants from their environment.¹⁸ The same trait that makes mudskippers vulnerable to pollution, their intimate contact with sediment through burrowing, feeding, and skin breathing, also makes them useful as biological indicators of coastal contamination. A population of healthy mudskippers is a reasonable sign that a mudflat is in decent ecological shape; their absence or contamination tells you something has gone wrong.

Mudskippers as a Window Into Vertebrate Evolution

Beyond their ecological interest, mudskippers attract attention because they offer a living analogy to one of the most consequential events in vertebrate history: the transition from water to land. Researchers have used the Japanese mudskipper as a model to explore how changing atmospheric oxygen concentrations during the Paleozoic Era, roughly 400 to 250 million years ago, might have influenced the emergence of the first tetrapods.¹⁹ Mudskippers are not ancestors of land vertebrates, and their lineage took a completely independent evolutionary path, but the biomechanical problems they solve on land are strikingly similar. Measurements of the ground reaction forces produced by mudskipper pectoral fins during their crutching gait have been directly compared to the forces produced by salamander limbs during walking, offering insights into what the earliest land vertebrate locomotion might have looked like.²⁰

This evolutionary angle adds a dimension to habitat conservation that goes beyond protecting a quirky fish. Mudskippers represent one of nature’s few successful experiments in fish-to-land transition happening right now, in real time, across dozens of species with different degrees of terrestriality. Losing the tidal habitats that support them would not just eliminate a group of animals but would erase a living laboratory for understanding how vertebrates first conquered dry ground.