Koi Goby (mudskipper type) – Periophthalmus spp.

Koi gobies of the mudskipper type, belonging to the genus Periophthalmus, are among the most fascinating brackish-water fish that an aquarist can keep. Combining the behavior of amphibious animals with the colour diversity of gobies, they offer a unique experience. They walk on land, climb roots and decor, and interact with their keeper in ways that few other aquarium fish can match. However, they also demand specific conditions. In this guide, we will explore how to care for them properly in home aquaria and what equipment is needed for long-term success.

Who Are the Koi Goby (Mudskipper Type) – Periophthalmus spp.?

Periophthalmus spp. are mudskipper-type gobies that inhabit mangroves, tidal flats, and brackish shorelines across Africa and Asia. The name “koi goby” is sometimes used in the aquarium trade for attractive, colourful or patterned mudskippers that remind people of koi in terms of variety and visual appeal, even though they are not koi carp at all. These fish have large, protruding eyes, muscular pectoral fins that function like legs, and the ability to breathe air through their skin and the lining of the mouth and gills.

In nature, they spend much of the day outside the water, resting on mud, roots, or rocks. Their bodies are adapted to this lifestyle: the skin must stay moist, and the gill chambers can retain water. When kept in aquaria, this dual lifestyle is exactly what fascinates aquarists. They can watch their fish patrol dry land, defend territory and even “beg” for food near the front glass.

The genus Periophthalmus includes several commonly traded species, such as Periophthalmus barbarus, P. novemradiatus, P. argentilineatus and others. Depending on the local market, they may appear under various trade names. It is important that the aquarist identifies the species as well as possible, because adult size and temperament can vary. Some species remain around 8–10 cm, while others can reach 15–20 cm and become quite robust.

Essential Aquarium Requirements for Mudskipper-Type Koi Gobies

Keeping Periophthalmus spp. is very different from maintaining a typical community aquarium. These fish require a carefully designed paludarium or riparium-style tank where both land and water are available. A standard fully filled aquarium is not suitable because mudskippers can drown if they cannot easily reach the surface or climb out of deep water areas.

The key elements of a proper mudskipper tank are:

• A shallow water zone with brackish conditions
• Extensive land or “mudflat” area where the fish can rest and move
• Access to open air at all times
• Effective filtration and stable water parameters
• Secure cover to prevent escape

A good basic rule is to keep the water depth between 10 and 20 cm for most Periophthalmus species, leaving enough vertical space above the surface for land structures and for the fish to climb. The land area can be made from sandbanks, rocks, driftwood, or specially designed platforms. Many aquarists use sloping beaches of fine sand that gradually rise above the waterline, mimicking a natural tidal flat. This allows gobies to choose their preferred position and makes maintenance easier.

Tank size should not be underestimated. For smaller species such as P. novemradiatus, a tank of at least 80–100 cm length can work for a small group, as long as enough land territory is provided. For larger species like P. barbarus, a length of 120 cm or more is recommended. These fish are very territorial and will need space to establish their own areas, especially males.

MB Store offers a wide selection of aquariums and aquarium equipment ideally suited for building such semi-terrestrial systems. With modern glass aquaria, stands, filters, and lighting systems available from MB Store, it is possible to design a custom mudskipper paludarium that safely accommodates both land and water environments while remaining visually appealing in the home or office.

Water Parameters, Brackish Setup and Filtration

Periophthalmus species are true brackish fish. They naturally inhabit waters where freshwater from rivers mixes with seawater, creating variable salinity. In the aquarium, stability is more important than precise duplication of those shifting conditions. Most mudskippers thrive at a specific gravity (SG) between 1.005 and 1.015, though some keepers prefer 1.010–1.015 for larger West African and Indo-Pacific species.

To create brackish water, always use high-quality marine salt mix formulated for reef or marine aquariums, never table salt or simple freshwater “tonic” salts. Dissolve the salt in dechlorinated water and measure with a refractometer or hydrometer. MB Store provides reliable filters, heaters, refractometers, and marine salt mixes, ensuring that aquarists can accurately maintain the right salinity and temperature for mudskippers.

Key water parameters include:

• Specific gravity: 1.005–1.015 depending on species
• Temperature: 24–28 °C (75–82 °F)
• pH: 7.5–8.3
• Hardness: moderate to hard
• Ammonia and nitrite: 0 ppm
• Nitrate: preferably below 40 ppm

Filtration must be efficient, yet water flow should not be too strong in the shallow areas where mudskippers rest. External canister filters, internal power filters or hang-on-back filters are all suitable, provided that the intake is protected so that fish cannot get trapped and that splashing does not soak the surrounding area. Many aquarists position spray bars or outlets along the back of the tank, allowing gentle circulation over the open water while leaving the land zones calm.

Because the water volume in mudskipper setups is often lower than in standard aquariums of the same size, the waste concentration can rise quickly. Regular partial water changes, thorough substrate cleaning in water zones, and removal of leftover food are crucial. Strong, stable biological filtration will prevent dangerous spikes in ammonia, which can damage sensitive gill tissues and skin.

Land Area Design, Décor and Equipment

The land section is what truly defines a koi goby mudskipper aquarium. The design should balance natural appearance with practicality and hygiene, offering the fish places to hide, climb, and bask, while allowing the keeper easy access for cleaning.

Common approaches to creating land areas include:

• Sandbanks: a sloping mound of fine sand raised above the waterline
• Rocky terraces made from stacked stones or artificial rock modules
• Large pieces of driftwood or mangrove roots emerging from the water
• Custom acrylic or plastic platforms covered with sand or gravel

The substrate above the water should be kept moist but not flooded. Mudskippers need their skin humid to breathe properly, yet they dislike being constantly submerged. Spraying the land area with aquarium water using a mister or spray bar can help. Some aquarists even incorporate small waterfalls or trickle features that keep selected surfaces damp. MB Store can supply the necessary pumps, spray bars, and other accessories to create these effects safely.

Décor should also provide hiding places. Caves formed from rockwork, sections of PVC pipe buried in the substrate, or hollow driftwood can serve as shelters. Mudskippers like to dig, so ensure that any stones or heavy decorations are stable and supported to avoid collapse. Lightweight artificial rock modules or resin structures can be very useful and are available in many designs.

Lighting can be moderate to bright, especially if you choose to grow plants in the water section or on the land. While many true mangrove plants are challenging for beginners, hardy brackish-tolerant plants such as certain Anubias, Java fern (in lower salinity systems), or even emergent houseplants in filters can be used. The fish themselves often show better colours under full-spectrum LED lighting. MB Store carries energy-efficient lighting systems that highlight the unique appearance of mudskippers while promoting natural day–night cycles.

A secure cover is absolutely essential. Mudskippers are skilled climbers and jumpers. They can easily escape through gaps around cables or filter outlets. Use tight-fitting lids, ensure that any holes are covered with mesh or plastic guards, and check regularly for weak points. At the same time, allow for adequate ventilation to prevent stagnant air and excessive humidity buildup that can cause condensation and mould.

Feeding and Nutrition for Koi Goby Mudskippers

Koi gobies of the Periophthalmus group are carnivorous opportunists. In the wild, they consume small invertebrates, insects, crustaceans, and even smaller fish that they catch on the mudflats or in shallow pools. In captivity, they usually adapt well to a varied diet of meaty foods.

Suitable foods include:

• Frozen or live bloodworms, blackworms and tubifex (used cautiously)
• Small pieces of shrimp, mussel, or fish fillet
• Brine shrimp and mysis shrimp
• High-quality pellets and sticks for carnivorous fish
• Crickets, fruit flies and other insects (from safe, pesticide-free sources)

Many keepers enjoy feeding mudskippers directly on the land area. Using feeding tongs or placing food on flat stones lets the fish display their natural foraging behaviour, hopping toward items and snapping them up. This method also keeps the water somewhat cleaner, since less food decomposes underwater.

Feed adult mudskippers once or twice per day in amounts they can consume quickly. Younger, growing individuals may require more frequent, smaller meals. Overfeeding should be avoided; these fish are greedy and will continue to eat even when already full, which can lead to obesity and poor water quality. Varying the diet is important to prevent nutritional deficiencies and to keep them stimulated.

Some mudskippers will eventually accept prepared commercial foods. Selecting high-quality brands rich in marine proteins and balanced vitamins supports long-term health, strong immune systems and vivid colours. MB Store carries a range of specialized fish food products suitable for carnivorous and brackish species, making it easy to assemble a diverse menu for your koi gobies.

Social Behavior, Tankmates and Compatibility

Mudskipper-type koi gobies are extremely entertaining to observe, largely because of their interactive and sometimes combative nature. They display to one another by raising dorsal fins, opening mouths and performing short chases. These behaviours are normal, but can escalate in confined spaces or when multiple dominant individuals are present.

When planning stocking, consider the following principles:

• Most Periophthalmus species are best kept in small groups or harems with more females than males.
• Provide multiple land territories separated by rocks or decor to break line of sight.
• Observe individuals closely at the beginning. Chronic bullying may require separation.

Choosing tankmates is challenging. Mudskippers often see anything that moves on land or near the surface as either a rival or potential prey. Small fish are at risk of being eaten, while larger or fast-moving species may stress the gobies. Brackish-tolerant fish that stay primarily in midwater or near the bottom and avoid the land zones can sometimes be kept with mudskippers under careful supervision.

Potential tankmates might include certain mollies, archerfish, or scats in large enough aquaria, but only if the system is spacious and structured to prevent competition. Many aquarists choose to keep Periophthalmus spp. in species-only setups for simplicity and welfare. This approach allows for more specialized care and reduces the risk of conflicts.

In addition to interactions with other fish, mudskippers often show interest in their human caretakers. They will frequently gather at the front of the tank, follow movements outside the glass, and quickly learn to associate people with feeding time. This high level of engagement is one reason they are so popular among experienced aquarists.

Health, Common Issues and Long-Term Care

Healthy mudskippers are alert, active on land, and display robust appetites. Their eyes should be clear and bright, the skin smooth without lesions, and fins intact. Many of the health problems that arise in captivity are preventable with proper husbandry.

Some common issues include:

• Skin infections from dirty, stagnant land areas or poor water quality
• Gill and fin damage from ammonia or nitrite spikes
• Injuries from aggressive fights or falls from high decorations
• Dehydration if the land area is too dry or hot

To minimize risks, maintain rigorous cleaning routines. Remove uneaten food quickly, siphon the shallow water zones regularly, and gently stir or replace the sand on land when it becomes fouled. Monitor temperature both in the water and the airspace above, as strong lighting can heat enclosed paludariums surprisingly quickly.

Quarantine new arrivals whenever possible. Many wild-caught Periophthalmus enter the trade stressed and may carry parasites or bacterial infections. A separate, smaller brackish tank can be used to observe them for several weeks before introduction to the main system. Using high-quality conditioning foods, stable salinity and low-stress surroundings during this period improves survival rates significantly.

Long-term success also depends on planning for adult size and behaviour. Juveniles sold in shops are often small and appear peaceful, but as they mature they claim territory vigorously. Upgrading tank size, adding more land zones, and adjusting group composition may be necessary. MB Store’s range of larger tanks, stands and filtration systems helps keepers respond to the evolving needs of their fish as they grow.

When properly cared for, koi goby mudskippers can live for several years, offering countless hours of observation and interaction. Their combination of terrestrial and aquatic lifestyles makes them ideal subjects for aquarists who enjoy designing complex environments and are willing to go beyond standard freshwater community tanks.

Planning Your Own Mudskipper System with MB Store

Building a dedicated mudskipper aquarium requires thoughtful planning, but it is entirely achievable for motivated hobbyists. Begin by deciding on the species you wish to keep and researching its adult size, preferred salinity, and temperament. Then select an aquarium with enough floor space for both water and land areas. A wider, longer tank is generally better than a tall one, since vertical water depth is less important than horizontal room.

MB Store offers complete aquarium sets as well as individual components, allowing aquarists to assemble a custom system. A typical mudskipper setup from MB Store products might include:

• A low, wide glass tank with sturdy stand
• High-capacity external filter with adjustable flow
• Submersible heater with reliable thermostat
• LED lighting unit suitable for both water and land
• Marine salt mix, refractometer, and water conditioners
• Decor materials like rocks, wood, and safe substrates

After installing and leak-testing the aquarium, create your land forms using sand, rocks and decor. Add brackish water gradually, ensuring that all equipment functions correctly and that the temperature and salinity are stable. Cycle the system fully before adding fish, seeding the filter with beneficial bacteria using starter cultures or filter media from an established tank if possible.

Once the tank is mature and water parameters tested, you can introduce your koi gobies. Observe them closely during the first days to ensure that they are using both land and water areas, feeding well, and not suffering from bullying. Adjust territories, décor placement, and hiding spots as needed to reduce stress and encourage natural behaviour.

With consistent maintenance and a willingness to learn from your fish, a Periophthalmus mudskipper aquarium can become the centerpiece of your fishkeeping hobby. The combination of specialized equipment and advice available from MB Store, together with your own patience and curiosity, forms the foundation for a successful and rewarding mudskipper experience.

FAQ

How big of a tank do I need for koi goby mudskippers?
For smaller Periophthalmus species, a tank at least 80–100 cm long is recommended for a small group, with shallow water and a wide land area. Larger species need 120 cm or more in length. Focus on floor space rather than height, and ensure multiple territories separated by decor to reduce aggression.

Do koi goby mudskippers have to live in brackish water?
Yes, most Periophthalmus mudskippers are true brackish fish and do best at a specific gravity around 1.005–1.015. Keeping them in pure freshwater long-term often leads to stress, disease and shortened lifespan. Always use proper marine salt mix, not table salt, and monitor salinity with accurate tools.

Can I keep mudskippers with other fish?
It is possible, but not always easy. Mudskippers are territorial and may harass or eat smaller fish. Suitable tankmates must tolerate brackish water, stay mostly in midwater or at the bottom, and avoid the land areas. Many aquarists choose species-only tanks for simplicity and better welfare.

What do koi goby mudskippers eat in the aquarium?
They are carnivores that enjoy frozen or live foods such as bloodworms, brine shrimp, mysis, chopped shrimp or fish, and quality carnivore pellets. Offering insects like crickets is also appreciated. Feed on land or in very shallow water to mimic natural hunting and keep the tank cleaner.

Are mudskippers suitable for beginners?
They are better suited to aquarists with some prior experience. Maintaining stable brackish conditions, designing safe land–water zones, and managing territorial behaviour is more complex than standard freshwater setups. With research and proper equipment, motivated beginners can succeed, but patience is essential.