Glassy Perchlets/Glassfishes (Ambassis sp.) part 1: A.kopsii, A.vachellii & A.interrupta

Glassy Perchlets/Glassfishes (Ambassis sp.)

A school of Singapore Glassy Perchlets.

Family: Ambassidae

Habitat: Brackish to saltwater. Open-water but enters mangroves during high tide.

There are currently 5 species in the genus Ambassis listed in the Third Edition of the Singapore Red Data Book. However, iNaturalist records and encounters prove that there are several more, with a few possibly being undescribed or in need of review. Common names refer to them as Glass/Glassy Perchlets or Glassfishes.

They're often seen as schools in the mid- to surface-water column picking off small invertebrates and other edibles they're not picky about as they're omnivorous. During a rising-high tide, some species commonly swim into mangrove swamps to forage and shelter among the roots. Some species are seen more often in and around mangroves while other species can be found in full saltwater as well around reefs, sometimes being trapped in tide pools. They are known to tolerate freshwater but are rarely seen in it locally.

Part 1 features: A.kopsii, A.vachellii and A.interrupta*

1. Singapore Glassy Perchlet (Ambassis kopsii)

A school of Singapore Glassy Perchlets feeding near the surface in Sungei Buloh Wetland Reserve. (Photograph by: Lumin Ong Jun Xiang)

Species Name(s): Ambassis kopsii

Common Name(s): Singapore Glassy Perchlet, Kops' Glassy Perchlet

Presence in Singapore: Native

Habitat: Brackish to full saltwater. Often easily seen near the surface along the shore.

Conservation status: Least Concern (Red Data Book 3)

This is the most common species of Ambassis one would encounter. It is recognized by its deep body, yellow-edged pelvic, anal and caudal fins, alongside a black spot on the first dorsal fin's tip. Reaching a maximum length of around 10cm, a school of them is easily seen from boardwalks as they hang out near the surface. While they frequent estuaries, they are also seen further out to sea and have been known to be trapped in tidal pools.

2. Vachell's Glassy Perchlet (Ambassis vachellii)

A school of Vachell's Glassy Perchlet seen along Bedok Jetty. (Photograph by: Lumin Ong Jun Xiang)

Species Name(s): Ambassis vachellii

Common Name(s): Vachell's Glassy Perchlet, Vachell's Glassfish

Presence in Singapore: Native

Habitat: Brackish to full saltwater. Often easily seen near the surface in mangrove creeks, tidal canals and open seawater around reefs etc.

Conservation status: Least Concern (Red Data Book 3)

The second most encountered Glassy Perchlet. This is a slimmer and smaller species that reaches a maximum length of around 6.5cm. Its slimmer build makes it stand out from other Ambassis species seen locally. Healthy individuals are usually a translucent grey with a sometimes a yellow tail. Infected individuals often have pale, solid colouration with dark patches (see photo below). They are sometimes seen together with A.kopsii in the same habitats but A.vachellii are frequently encountered further out to sea as well. They have been seen following flotsam, foraging along jetties and pontoons above reefs etc.

A school of Vachell's Glassy Perchlets. Sick individuals can be seen with prominent dark patches. (Photograph by: Lumin Ong Jun Xiang)

Feeding frenzy! Vachell's Glassy Perchlets feeding below a concrete boardwalk with Javanese Ricefishes.

3. Longspine Glassy Perchlet (Ambassis interrupta)

A dead Longspine Glassy Perchlet seen in Sungei Buloh Wetland Reserve. (Photograph by: Lumin Ong Jun Xiang)

Species Name(s): Ambassis interrupta

Common Name(s): Longspine Glassy Perchlet, Longspine Glassfish

Presence in Singapore: Native

Habitat: Brackish to full saltwater. Seen more in larger channels.

Conservation status: Least Concern (Red Data Book 3)

 

The Longspine Glassy Perchlet inhabits the same habitats as the other featured two species but is seen more often in larger channels such as rivers, which it swims up during a high tide. Inferencing from local sightings, it is not photographed much in-situ.

The Longspine Glassy Perchlet looks similar to the Vachell's Glassy Perchlet at first glance but can be identified by its long dorsal spine and deep body.

References

• FishBase. Ambassis kopsii Bleeker, 1858 – (Singapore glassy perchlet). Retrieved from https://www.fishbase.se/summary/Ambassis-kopsii.html
• FishBase. Ambassis interrupta Bleeker, 1858 – (Long-spined glassfish). Retrieved from https://www.fishbase.se/summary/Ambassis-interrupta.html
• FishBase. Ambassis vachellii Richardson, 1846 – (Vachelli's glass perchlet). Retrieved from https://www.fishbase.se/summary/Ambassis-vachellii.html
• Lim, K.K.P. & Low, J.K.Y. 1998. A Guide to Common Marine Fishes of Singapore. Singapore Science Centre, 163 pp. ISBN 981-00-9904-5.
•  Lin JY, Ong JXL, Tay JX & Tan HH (2024) Biodiversity Record: Fishes and other marine life observed among flotsam at Marina South. Nature in Singapore, 17: e2024128. DOI: 10.26107/NIS-2024-0128
• National Parks Board (NParks). Marine Fishes. Retrieved from https://www.nparks.gov.sg/nature/species-list/marine-fishes.

Cantor's Gudgeon (Ophiocara cantoris)

Cantor's Gudgeon (Ophiocara cantoris)

A colourful Cantor's Gudgeon found in Berlayer Creek.

Family: Butidae

Species Name(s): Ophiocara cantoris
Common Name(s): Cantor's Gudgeon

Presence in Singapore: Native
Habitat: Brackish to freshwater. Mangrove creeks, pools and tidal canals etc. 
Conservation status: Near Threatened (Red Data Book 3)

The Cantor's Gudgeon is a commonly-seen mangrove fish that one might mistaken for a fat goby. Its usual colouration is a distinct brown with two white vertical white bands, accompanied by whitish-yellow dots throughout the body. It can also appear fully dark brown as well, which is often seen in larger individuals. The average length of this fish is around 9 to 11cm but like its relative Ophiocara ophicephalus, it can probably grow to twice the average length.

The Cantor's Gudgeon is an ambush predator, hovering slowly in the water column or among shelter such as mangrove roots and leaf litter. It waits for small fishes and invertebrates to get close before snapping them up with a burst of speed.

In the Third Edition of the Singapore Red Data Book, it is referred to as Ophiocara porocephala and it is also referred to as O.ophicephalus in past records. O.cantoris should be the current correct name for the local species as a review of all 3 species differentiates them at the genetic and morphological level (Keith & Mennesson, 2021). 

A large Cantor's Gudgeon seen in Pasir Ris. Note the faded stripes.

A juvenile Cantor's Gudgeon seen in Pasir Ris. (Photograph by: Lumin Ong Jun Xiang)

References

• Lim, K.K.P. & Low, J.K.Y. 1998. A Guide to Common Marine Fishes of Singapore. Singapore Science Centre, 163 pp. ISBN 981-00-9904-5.
• National Parks Board (NParks). Marine Fishes. Retrieved from https://www.nparks.gov.sg/nature/species-list/marine-fishes.
• Philippe Keith, Marion I. Mennesson. Review of Ophiocara (Teleostei: Butidae) from Indo-Pacific Islands. Cybium : Revue Internationale d’Ichtyologie, 2021, ⟨10.26028/cybium/2021-452-002⟩. ⟨hal-03337214⟩

Crescent Grunter (Terapon jarbua)

Crescent Grunter (Terapon jarbua)

A school of Crescent Grunters investigating a fallen snake shed in Berlayer Creek.

Family: Terapontidae

Species Name(s): Terapon jarbua

Common Name(s): Crescent Grunter, Target Fish, Spiky Trumpeter, Tiger Perch
Presence in Singapore: Native

Habitat: Freshwater to Marine.
Conservation status: Least Concern (Red Data Book 3)

The Crescent Grunter is a euryhaline fish that can be found in a wide range of salinities from full marine to freshwater. It spawns in saltwater, where juveniles hang out in intertidal zones but also swim up estuaries and rivers alongside adults. This commonly sighted fish can grow to a maximum known length of 36cm but usually average around 25cm. This species' distinctive patterning especially from the top gives it one of its many common names - the Target Fish.

This fish is mostly carnivorous, hunting invertebrates and smaller fish near the bottom but will also eat algae. They are also known ectoparasites, feeding on the scales of larger fishes which makes them horrible community fishes in most aquariums. Commercially, this fish is sold usually fresh or dry and salted.

Adult males guard and fan their eggs. Juveniles are also known to be territorial and establish territories via excavating craters. The name "Grunter" and "Trumpeter" comes from their ability to make noise using their swim bladder, which they use for communication.



References

• FishBase. Terapon jarbua (Fabricius, 1775) – (Jarbua terapon). Retrieved from https://fishbase.se/summary/Terapon_jarbua.html
• Lim, K.K.P. & Low, J.K.Y. 1998. A Guide to Common Marine Fishes of Singapore. Singapore Science Centre, 163 pp. ISBN 981-00-9904-5.
• National Parks Board (NParks). Marine Fishes. Retrieved from https://www.nparks.gov.sg/nature/species-list/marine-fishes.

Grey Knight Goby (Stigmatogobius sadanundio)

Grey Knight Goby (Stigmatogobius sadanundio)

A pair of Grey Knight Gobies hovering in a mangrove creek in Pasir Ris. (Photograph by: Lumin Ong)

Family: Oxudercidae: Gobionellinae

Species Name(s): Stigmatogobius sadanundio
Common Name(s): Grey Knight Goby

Presence in Singapore: Native
Habitat: Brackish and freshwater. Mangrove creeks and pools.
Conservation status: Least Concern (Red Data Book 3)

This is one of the more prominent mangrove gobies one will spot from above water due to its size! The Grey Knight Goby is decently-sized compared to its neighbours and grow to a maximum known length of 9cm. It is common and often seen hovering in shallow mangrove creeks and pools during low tide. 

It is known to prefer lower salinity levels and are more abundant in the back mangroves, with younger individuals being spotted in freshwater. This carnivorous species is an active predator which feeds on smaller fish and invertebrates. Its rarer cousin, the Peach Knight Goby (Stigmatogobius pleurostigma) can look similar and would require a clear view of the tail for identification. A solid spot would be present at the bottom of the tail for that species! 

The Grey Knight Goby is also a commonly sold aquarium fish and is frequently included in brackish community tanks.

A large Grey Knight Goby - note the lack of solid spot at the bottom of the tail.

A small juvenile found in a freshwater drain on Pulau Ubin.

References

• FishBase. Stigmatogobius sadanundio (Hamilton, 1822) – (Knight goby). Retrieved from https://www.fishbase.se/summary/Stigmatogobius-sadanundio.html
• Lim, K.K.P. & Low, J.K.Y. 1998. A Guide to Common Marine Fishes of Singapore. Singapore Science Centre, 163 pp. ISBN 981-00-9904-5.
• National Parks Board (NParks). Marine Fishes. Retrieved from https://www.nparks.gov.sg/nature/species-list/marine-fishes.

Snubnose Gobies (Pseudogobius sp.)

Snubnose Gobies (Pseudogobius sp.)

The most commonly seen snubnose goby - Pseudogobius poicilosoma.

Family: Oxudercidae: Gobionellinae

Habitat: Brackish to freshwater. Mudflats, tidal creeks, mangrove pools etc.

The genus Pseudogobius has 7 species recorded in the third edition of Singapore's Red Data Book. These gobies are usually small, averaging out between 2 and 6cm. Species such as the Spotted Snubnose Goby (Pseudogobius poicilosoma) can be found in almost every estuarine habitat across different salinity ranges, while other species such as Pseudogobius melanosticta appear to prefer near freshwater salinity. All species pick small invertebrates off the sediment or whatever surface they're on. 

1. Spotted Snubnose Goby (Pseudogobius poicilosoma)

Blue arrow: the blue dot on the dorsal fin that makes this species easy to ID!

Species Name(s): Pseudogobius poicilosoma
Common Name(s): Spotted Snubnose Goby, Northern Fatnose Goby

Presence in Singapore: Native
Habitat: Various estuarine habitats from near freshwater to full marine salinity.
Conservation status: Least Concern (Red Data Book 3)

This is the most abundant snubnose goby one will encounter in our estuaries and also one of the most common gobies too. An ideal angle would reveal a blue dot on the dorsal fin, which distinguishes this species from the rest. The vertical black stripes and lack of a yellow peduncle also helps narrow down this species.

2. Blackline Snubnose Goby (Pseudogobius verticalis)

A Blackline Snubnose Goby displaying the yellow peduncle and dorsal fin colouration.

Species Name(s): Pseudogobius verticalis
Common Name(s): Blackline Snubnose Goby

Presence in Singapore: Native
Habitat: Brackish. Mangrove pools and creeks.
Conservation status: Near Threatened (Red Data Book 3)

This species is often seen alongside the Spotted Snubnose Goby and similar-looking Yellowfin Snubnose Goby (Pseudogobius fulvicaudus). 

Both the Blackline Snubnose Goby and Yellowfin Snubnose Goby possess a yellow peduncle, alongside fins with significant portions of yellow. The first dorsal fine of the Blackline Snubnose Goby is a vertical stripe of black against yellow something like the photo on the right. 

A relatively colourful Blackline Snubnose Goby showing off its fins!

3. Yellowfin Snubnose Goby (Pseudogobius fulvicaudus)

A Yellowfin Snubnose Goby flaring at another individual, showing off the ID features!

Species Name(s): Pseudogobius fulvicaudus
Common Name(s): Yellowfin Snubnose Goby

Presence in Singapore: Native
Habitat: Brackish. Mangrove pools and creeks.
Conservation status: Near Threatened (Red Data Book 3)

Another colourful snubnose goby that is similar-looking to the Blackline Snubnose Goby, which it shares a yellow peduncle with. The first dorsal fin has a horizontal 
yellow stripe in the middle of two black stripes as shown on the right.

A closer look at the Yellowfin Snubnose Goby.

4. Black-spotted Snubnose Goby (Pseudogobius melanosticta)

A Black-spotted Snubnose Goby showing off its black cheek stripes.

Species Name(s): Pseudogobius melanosticta
Common Name(s): Black-spotted Snubnose Goby

Presence in Singapore: Native
Habitat: Brackish, near freshwater. Mangrove pools and creeks.
Conservation status: Near Threatened (Red Data Book 3)

A lesser seen snubnose goby but distinct from the rest presented so far. This species is noted to inhabit salinities nearer to freshwater. The black cheek stripe is slanted in this species and the dorsal fin is tall, with two black stripes ending in black blotch at the end. 

A Black-spotted Snubnose Goby displaying its tall dorsal fin clearly! (Photograph by: Zick Soh)

5. Avicennia Snubnose Goby (Pseudogobius avicennia)

Species Name(s): Pseudogobius avicennia

Common Name(s): Avicennia Snubnose Goby

Presence in Singapore: Native
Habitat: Brackish. Mangrove fringes, pools and creeks.
Conservation status: Near Threatened (Red Data Book 3)

Another lesser seen species of snubnose goby thought to prefer living near and along the fringes of mangroves. This species is identified by the presence of a distinct, black ocellus on the peduncle (labelled with a white arrow on the right).

This species has been observed foraging on mangrove roots during high tide as seen in https://www.inaturalist.org/observations/316740558. 

Not yet encountered:

• Masago Snubnose Goby (Pseudogobius masago)
• Barfin Snubnose Goby (Pseudogobius yanamensis)

 


References

• Larson, H. K., & Hammer, M. P. (2021). A revision of the gobiid fish genus Pseudogobius (Teleostei: Gobiidae: Tridentigerinae), with description of seven new species from Australia and South-east Asia.
• Lim, K.K.P. & Low, J.K.Y. 1998. A Guide to Common Marine Fishes of Singapore. Singapore Science Centre, 163 pp. ISBN 981-00-9904-5.
• National Parks Board (NParks). Marine Fishes. Retrieved from https://www.nparks.gov.sg/nature/species-list/marine-fishes.
• Ong JXL (2024) Biodiversity Record: Gobies in mangrove tide pools at Sungei Buloh Wetland Reserve. Nature in Singapore, 17: e2024035. DOI: 10.26107/NIS-2024-0035
• Ong JXL (2025) Biodiversity Record: Aggressive conspecific interactions of two species of mangrove gobies. Nature in Singapore, 18: e2025040. DOI: 10.26107/NIS-2025-0040

Roux's Dwarf Goby (Pandaka rouxi)

Roux's Dwarf Goby (Pandaka rouxi)

A lone Roux's Dwarf Goby seen in Pasir Ris Park.

Family: Oxudercidae: Gobionellinae

Species Name(s): Pandaka rouxi
Common Name(s): Roux's Dwarf Goby, Roux's Pygmy Goby

Presence in Singapore: Native
Habitat: Brackish. Mangrove creeks and pools.
Conservation status: Near Threatened (Red Data Book 3)

This is one of our smallest native fishes! They are only rivalled by glass gobies in the genus Gobiopterus. The largest known individual reached a length of 1.8cm but they usually average out at just 1cm. They can be found freely swimming in mangrove creeks and pools, where their salinity preference is brackish.

They are closely related to bumblebee gobies of the genus Brachygobius and are also similiar in appearance. They are definitely smaller however, with incomplete stripes and blots alongside an mostly orange dorsal fin. At this size, they usually feed on zooplankton.

They are occasionally available in the aquarium trade as an interesting choice for nano aquariums. They do not live long in freshwater. 

A mix of Kabili Bumblebee Gobies, Glass Gobies and a lone Roux's Dwarf Goby circled in blue.

References

• Aquarium Glaser GmbH. Pandaka rouxi – (dwarf goby). Retrieved from https://www.aquariumglaser.de/en/25-perchlike-fishes/pandaka-rouxi-2/
• National Parks Board (NParks). Marine Fishes. Retrieved from https://www.nparks.gov.sg/nature/species-list/marine-fishes.

Blue-eyed Mullet-goby (Hemigobius melanurus)

 Blue-eyed Mullet-goby (Hemigobius melanurus)

A mature Blue-eyed Mullet-goby found in a mangrove pool in Admiralty Park.

Family: Oxudercidae: Gobionellinae

Species Name(s): Hemigobius melanurus, Hemigobius mingi
Common Name(s): Blue-eyed Mullet-goby, Banded Goby

Presence in Singapore: Native
Habitat: Brackish but also inhabits freshwater. Mangrove creeks and pools.
Conservation status: Near Threatened (Red Data Book 3)

The Blue-eyed Mullet-goby is common in our mangrove forests, being found easiest in creeks and pools revealed during low tide. It makes itself rather visible by hanging out near the surface, staring at the sky like it's in a daze. It seems to prefer living in the back half of the mangroves, where the salinity is a closer to freshwater but is adaptable like most estuarine gobies.

Mature individuals have a unique dirty brown with bands that fade past halfway down the body. Juveniles can be confused for bumblebee gobies in the genus Brachygobius, but have possess more bands which are thinner and also orange dorsal fins. This goby has been observed grazing on surfaces but are also known to be opportunistic feeders on small invertebrates.

*It is noted that Hemigobius melanurus is synonymous with Hemigobius mingi.

A mature Blue-eyed Mullet-goby grazing on a mangrove root, offering a lateral view.

A juvenile Blue-eyed Mullet-goby displaying behaviour typical of this species - staring at the sky.

References

• Larson, H. K. (1999). A Review of the Mangrove Goby Genus Hemigobius (Gobioidei, Gobiidae, Gobionellinae). The Beagle, Records of the Museums and Art Galleries of the Northern Territory, 15, 23–42. Retrieved from https://www.researchgate.net/publication/354335932_A_Review_of_the_Mangrove_Goby_Genus_Hemigoius_Gobioidei_Gobiidae_Gobionellinae
• Lim, K.K.P. & Low, J.K.Y. 1998. A Guide to Common Marine Fishes of Singapore. Singapore Science Centre, 163 pp. ISBN 981-00-9904-5.
• National Parks Board (NParks). Marine Fishes. Retrieved from https://www.nparks.gov.sg/nature/species-list/marine-fishes.
• World Register of Marine Species (WoRMS). Hemigobius melanurus (Bleeker, 1849). Retrieved from https://www.marinespecies.org/aphia.php?p=taxdetails&id=314573

Banded Mullet-goby (Hemigobius hoevenii)

Banded Mullet-goby (Hemigobius hoevenii)

A male Banded Mullet-goby foraging in a mangrove pool. (Sungei Buloh Wetland Reserve)

Family: Oxudercidae: Gobionellinae

Species Name: Hemigobius hoevenii
Common Name(s): Banded Mullet-goby

Presence in Singapore: Native
Habitat: Brackish but also inhabits freshwater. Mangrove creeks and pools.
Conservation status: Least Concern (Red Data Book 3)

A common species seen in our mangroves! The Banded Mullet-goby is recognizable by its slanting bands and the presence of an ocellus on both sides of the peduncle. Males appear to have orange dorsal and caudal fins, while the females' possess a mix of white-yellow and black. The margins of the dorsal fins are never white, which helps to separate it from other mangrove gobies. It is a small species, growing to a maximum length of 6cm but the average individual is half that size.

As with most mangrove gobies, it is found in creeks and pools left behind during low tide. It can also be seen inhabiting the burrows of other animals such as large mudskippers. It can live in varying salinities between fresh and brackish water. They forage by sifting through sediment or opportunistically catching prey such as small invertebrates. 

Typical Banded Mullet-goby individual at night. (Pasir Ris)

A (supposedly) female Banded Mullet-goby. Note the ocellus on the peduncle and slanting bands. (Pasir Ris)

References

• FishBase. Hemigobius hoevenii (Bleeker, 1851) – (Banded mulletgoby). Retrieved from https://www.fishbase.se/summary/Hemigobius-hoevenii.html
• Lim, K.K.P. & Low, J.K.Y. 1998. A Guide to Common Marine Fishes of Singapore. Singapore Science Centre, 163 pp. ISBN 981-00-9904-5.
• National Parks Board (NParks). Marine Fishes. Retrieved from https://www.nparks.gov.sg/nature/species-list/marine-fishes.

Kabili Bumblebee Goby (Brachygobius kabiliensis)

Kabili Bumblebee Goby (Brachygobius kabiliensis)

One of several Kabili Bumblebee Gobies found in an isolated mangrove pool during low tide. (Admiralty Park)

Family: Oxudercidae: Gobionellinae

Species Name: Brachygobius kabiliensis
Common Name(s): Kabili Bumblebee Goby, Mangrove Bumblebee Goby

Presence in Singapore: Native
Habitat: Brackish but can also be found in freshwater. Mangrove creeks and pools.
Conservation status: Near Threatened (Red Data Book 3)

Bumblebee Gobies are popular in the aquarium trade due to their small sizes and big personalities, partnered with attractive patterning that give them the name! The Kabili Bumblebee Goby is likely to be the only native Brachygobius species found in Singapore, where they are common throughout the mangrove swamps. It is definitely easier to see them during low tide in pools and creeks, or even the burrows of other animals such as Giant Mudskippers (Periophthalmodon schlosseri).

"Easier to see" might be an overstatement from the raised trails and boardwalks of our local mangroves. The Kabili Bumblebee Goby is tiny, growing up to a maximum length of only under 2cm. It looks similar to other Brachygobius but has noticeably more bands and a smaller size. It is observed that the colouration and patterning is variable in intensity. In Singapore, Brachygobius sabanus and B.doriae are considered to be introduced but don't seem to mix with the featured native.

Like its relatives, the Kabili Bumblebee Goby is a predator of small invertebrates such as worms and crustaceans. They are often seen either sticking to the substrate and other surfaces, or "hovering" in the water column.

Several Kabili Bumblebee Gobies from Pasir Ris showing more solid bands and a brighter yellow! (Photograph by: Lumin Ong Jun Xiang)

A mangrove goby community in the burrow of a Giant Mudskipper. Kabili Bumblebee Gobies  make up half the picture! (Sungei Buloh Wetland Reserve)

References

• FishBase. Brachygobius kabiliensis (Fowler, 1937) – (Kabili bumblebee goby). Retrieved from https://www.fishbase.se/summary/25067
• Lim, K.K.P. & Low, J.K.Y. 1998. A Guide to Common Marine Fishes of Singapore. Singapore Science Centre, 163 pp. ISBN 981-00-9904-5.
• Lim, K. K. P., & Tan, H. H. 2012. Addition of fish species to the established alien fauna of Singapore: Amblypharyngodon chulabhornnae and Brachygobius sabanus. Nature in Singapore 5: 69–72. Retrieved from https://lkcnhm.nus.edu.sg/app/uploads/2017/06/2012nis069-072.pdf
• National Parks Board (NParks). Marine Fishes. Retrieved from https://www.nparks.gov.sg/nature/species-list/marine-fishes.

Elongate Mudskipper (Pseudapocryptes elongatus)

Elongate Mudskipper (Pseudapocryptes elongatus)

An adult Elongate Mudskipper found in a back mangrove creek.

Family: Oxudercidae (Subfamily Oxudercinae - Mudskippers)

Species Name: Pseudapocryptes elongatus
Common Name(s): Elongate Mudskipper

Presence in Singapore: Native
Habitat: Coastal: Mangrove forest creeks down to mudflats.
Conservation status: Vulnerable (Red Data Book 3)

This is one of the lesser encountered mudskipper species in Singapore. This is a long species as evident by its common name, reaching up to a maximum length of 24cm. The Elongate Mudskipper has well-proportioned fins which aren't flashy like its relatives. Both juveniles and adults have varying levels of slanted stripes on a greenish-brown/grey body. While they have been recorded living down in the mudflats, sightings of them in Singapore seem to be limited to back mangrove creeks such as in Pulau Ubin, where they're most often seen. In 2024, juveniles of the Elongate Mudskipper were found to be living in the open breakwater of Marina East by us, where they have burrows in the muddy pools present. With adults being sighted before in the same area, it is a surprising habitat considering their preferences but they seem to be thriving.

Elongate Mudskippers are omnivorous, feeding on algae and small invertebrates such as worms. As mentioned in (Polgar, 2013), they have a few feeding styles such as sifting (like the Bearded Mudskipper), scraping (like the Boddart's Blue-spotted Mudskipper) and pump-suspension feeding where they inhale suspended particles. This species is the most aquatic of all mudskippers seen reliably in Singapore, preferring to sit under water with only its eyes breaching the surface. 

A juvenile Elongate Mudskipper from Marina East. (Photograph by: Jiayuan Lin)

A juvenile Elongate Mudskipper which without Jiayuan's side shot, it might've been impossible to ID.

Check out this video: https://www.youtube.com/watch?v=SfArKeBzsVE&ab_channel=SGfishesabovewater



References

• FishBase. Pseudapocryptes elongatus Cuvier, 1816 – (Mudskipper). Retrieved from https://fishbase.se/summary/Pseudapocryptes-elongatus
• Lim, K.K.P. & Low, J.K.Y. 1998. A Guide to Common Marine Fishes of Singapore. Singapore Science Centre, 163 pp. ISBN 981-00-9904-5.
• National Parks Board (NParks). Marine Fishes. Retrieved from https://www.nparks.gov.sg/nature/species-list/marine-fishes.
• Ong JXL, Tay JX & JY Lin (2025) Biodiversity Record: Elongate mudskippers, Pseudapocryptes elongatus, at Marina East. Nature in Singapore, 18: e2025010. DOI: 10.26107/NIS-2025-0010
• Polgar, G. Gobiidae: Oxudercinae – Pseudapocryptes elongatus Cuvier, 1816. Retrieved from http://www.mudskipper.it/SpeciesPages/elon.html 

Bearded Mudskipper (Scartelaos histophorus)

Bearded Mudskipper (Scartelaos histophorus)

A mated pair of Bearded Mudskippers.

Family: Oxudercidae (Subfamily Oxudercinae - Mudskippers)

Species Name: Scartelaos histophorus
Common Name(s): Bearded Mudskipper, Walking Goby

Presence in Singapore: Native
Habitat: Coastal: Open mudflats and creek banks.
Conservation status: Vulnerable (Red Data Book 3)

One of Singapore's lesser encountered mudskippers due to its habitat preference. The Bearded Mudskipper is easily recognized by its elongated body shape which can reach up to 14cm in length. It is overall grey with sparse black dots. The first dorsal fin is very tall and it is raised in territorial displays as with all mudskippers. The unique feature about this species is that it has barbels below its head, resulting in the common name.

The Bearded Mudskipper is mostly encountered on open mudflats where the mud is sticky and one can sink in it to varying levels. They can also be encountered further upstream along creek banks but larger individuals are further out to sea. Similar to the Boddart's Blue-spotted Mudskipper, they only appear during low tide and hide in their burrows where there is an air pocket during high tide. This species is omnivorous and it feeds by sifting through the mud, running it through its gills and expelling the sediment. It feeds on tiny organisms such as algae, crustaceans and worms.

They are known for their impressive displays where the male leaps into the air but keeps its tail on the ground, making it seem like it is standing up! If a female is interested, they share a burrow together. It appears that juveniles are not as elongated and have the normal mudskipper proportions.

A Bearded Mudskipper sifting through the mud for food.

A small Bearded Mudskipper that has just emerged from its burrow.

YouTube videos

• Passive behaviour: https://www.youtube.com/watch?v=BWEUVAqJFzw&ab_channel=SGfishesabovewater
• Burrow emergence: https://www.youtube.com/watch?v=9MdIDaMvDUs&ab_channel=SGfishesabovewater

References

• FishBase. Scartelaos histophorus Valenciennes, 1837 – (Walking goby). Retrieved from https://www.fishbase.se/summary/Scartelaos-histophorus.html
• Lim, K.K.P. & Low, J.K.Y. 1998. A Guide to Common Marine Fishes of Singapore. Singapore Science Centre, 163 pp. ISBN 981-00-9904-5.
• National Parks Board (NParks). Marine Fishes. Retrieved from https://www.nparks.gov.sg/nature/species-list/marine-fishes.

Boddart's Blue-spotted Mudskipper (Boleophthalmus boddarti)

Boddart's Blue-spotted Mudskipper (Boleophthalmus boddarti)

A mature Boddart's Blue-spotted Mudskipper flaring its fins

Family: Oxudercidae (Subfamily Oxudercinae - Mudskippers)

Species Name: Boleophthalmus boddarti
Common Name(s): Boddart's Blue-spotted Mudskipper, Boddart's Goggle-eyed Goby, Blue-spotted Mudskipper

Presence in Singapore: Native
Habitat: Coastal: Open mudflats near and beyond the mangrove roots.
Conservation status: Vulnerable (Red Data Book 3)

This genus of large mudskippers are unmistakable for they are commonly filmed for documentaries due to their range of behaviours. The Boddart's Blue-spotted Mudskipper can reach a maximum recorded length of 22cm and can be separated from other blue-spotted mudskippers via its slanting black stripes. As its name suggests, both the sides of the body and fins are covered in blue spots. Their dorsal fins are impressive with long, filamentous spines.

A small Boddart's Blue-spotted Mudskipper found in Sungei Buloh Wetland Reserve.

The Boddart's Blue-spotted Mudskipper lives out on the open mudflats that are revealed during low tide beyond the mangrove trees. Larger individuals are found further out than smaller individuals, which reside closer to the trees. During high tide, this species hide in their burrows where there is an air pocket inside. 

This mudskipper has a stocky build which it smoothly drags across the mudflats it calls home. Its large mouth appears to be more for burrowing and fighting rather than capturing prey, for it leads a herbivorous and detritivorous lifestyle. To feed, they skim the mud by moving their heads side to side, scraping up the microbes present on the surface such as algae.

Males put on a beautiful display by jumping into the air with fins fully flared, in hopes of attracting a female. If a female is interested, they enter the burrow together to mate. Very small juveniles are pinkish (see Ong & Tay, 2024). 

Mudskippers roll on their sides to keep themselves moist!

A juvenile Boddart's Blue-spotted Mudskipper.

Emerging from its burrow. It has two entrances!

References

• FishBase. Boleophthalmus boddarti (Pallas, 1770) – (Boddart's goggle-eyed goby). Retrieved from https://fishbase.se/summary/4901
• Lim, K.K.P. & Low, J.K.Y. 1998. A Guide to Common Marine Fishes of Singapore. Singapore Science Centre, 163 pp. ISBN 981-00-9904-5.
• National Parks Board (NParks). Marine Fishes. Retrieved from https://www.nparks.gov.sg/nature/species-list/marine-fishes.
• Ong JXL & Tay JX (2024) Biodiversity Record: Fish fauna of a mangrove tide pool at Sungei Buloh. Nature in Singapore, 17: e2024056. DOI: 10.26107/NIS-2024-0056

Dusky-gilled Mudskipper (Periophthalmus variabilis)

Dusky-gilled Mudskipper (Periophthalmus variabilis)

A small Dusky-gilled Mudskipper on the sandy shores of St John's Island.

Family: Oxudercidae (Subfamily Oxudercinae - Mudskippers)

Species Name: Periophthalmus variabilis
Common Name(s): Dusky-gilled Mudskipper

Presence in Singapore: Native
Habitat: Coastal: Mangrove forests down to lower intertidal zones.
Conservation status: Vulnerable (Red Data Book 3)

The Dusky-gilled Mudskipper is a small species, reaching a maximum total length of 7cm. This species is identified by its variable black blotches that usually fade towards the bottom. It also has tiny whitish-blue spots across the body. Its red dorsal fins are similar to the Silver-lined Mudskipper but in the first dorsal fin, the black margin curves down to the base and it lacks the many white specks. 

The Dusky-gilled Mudskipper was formerly synonymized with Periophthalmus novemradiatus, leading to some outdated signboards in our parks. It is now a recognized separate species from its relative further north. 

This species shares a similar habitat range to most of its relatives, being abundant in back mangroves all the way down to intertidal zones. It doesn't seem to stray far from the shelter of mangroves however unlike the Gold-spotted Mudskipper. It is an opportunistic carnivore that feeds on small invertebrates.

Territorial display of a Dusky-gilled Mudskipper with dorsal fins in full view.

References

• FishBase. Periophthalmus variabilis Eggert, 1935 – (mudskipper). Retrieved from https://fishbase.se/summary/65362
• Lim, K.K.P. & Low, J.K.Y. 1998. A Guide to Common Marine Fishes of Singapore. Singapore Science Centre, 163 pp. ISBN 981-00-9904-5.
• National Parks Board (NParks). Marine Fishes. Retrieved from https://www.nparks.gov.sg/nature/species-list/marine-fishes.

Slender Mudskipper (Periophthalmus gracilis)

 Slender Mudskipper (Periophthalmus gracilis)

A Slender Mudskipper seen on the sandy shores of St John's Island.

Family: Oxudercidae (Subfamily Oxudercinae - Mudskippers)

Species Name: Periophthalmus gracilis
Common Name(s): Slender Mudskipper, Graceful Mudskipper

Presence in Singapore: Native
Habitat: Coastal: Mangrove forests down to lower intertidal zones.
Conservation status: Vulnerable (Red Data Book 3)

The Slender Mudskipper is a small species, reaching a maximum recorded length of 4.5cm. This species usually has thin, silver stripes and slanting black bands on the side of its body, making it easy to confuse with the Silver-lined Mudskipper and Dusky-gilled Mudskipper. The best way to identify this mudskipper is to look at the gap between its two dorsal fins, which are very far part compared to its relatives. The first dorsal fin is also small and rectangular, with dark patterns and blue margins over a lighter colour base compared to the red base of the two earlier mentioned species.

This is a common species, being seen in the back mangroves down to open intertidal zones such as mudflats. It is often seen alongside its relatives listed in this blog as well. Being an opportunistic carnivore, it preys on small invertebrates. 

A Slender Mudskipper caught via hand-line for dorsal fin inspection. (Photograph by: Jiayuan Lin)

References

• FishBase. Periophthalmus gracilis Eggert, 1935 – Graceful (Slender) Mudskipper. Retrieved from https://www.fishbase.se/summary/Periophthalmus-gracilis
• Lim, K.K.P. & Low, J.K.Y. 1998. A Guide to Common Marine Fishes of Singapore. Singapore Science Centre, 163 pp. ISBN 981-00-9904-5.
• National Parks Board (NParks). Marine Fishes. Retrieved from https://www.nparks.gov.sg/nature/species-list/marine-fishes.