Sarawak, Borneo

By Peter Petersen

A photo article with wildlife observations from the Malaysian state Sarawak in Borneo. 

The endemic Proboscis monkey (Nasalis larvatus).


This is not what people usually associate with a large city like Kuching. But you choose your own view on life and this is one of my first shots from the city. An unidentified climbing plant on a tree trunk.

The Asian House Gecko (Hemidactylus frenatus) is common around Kuching in Sarawak. This species seem to feed mainly on cockroaches which is probably why they thrive amongst human settlements.

The largest specimens of the Asian House Gecko (Hemidactylus frenatus) we found, were around 12 cm TL.

Another animal which do well in cities is as Kuching is the Asian Common Toad (Duttaphrynus melanostictus). This species is feeding mainly on cockroaches, flies and crickets.

The Oriental Latrine Fly (Chrysomya megacephala) is very common here. Notice the extremely large eyes. This species is an important food item for many of the reptiles and amphibians in the city.

On a night walk in the reservoir park Kuching we noticed Bighead catfishes (Clarias macrocephalus) in the reservoirs. This species is introduced and as a consume fish.

We also found the Marble goby (Oxyeleotris marmorata) in here. This species is widespread and native to this area as well. This predator rests on the bottom and ambush smaller fish.

The Malayan Lacewing Butterfly (Cethosia hypsea hypsea) has a wingspan of around 8 cm. This species is poisonous both as larvae and imago (adult). The larvae feed on a passionflower plants belonging to the genus Adenia.

The Green Paddy Frog (Hylarana erythraea) female grow to around 7-8 cm while males only reaches 4-5 cm. This species is very common in Sarawak.

This Red Bearded Flying Lizard (Draco haematopogon) flew over our heads and landed in a nearby tree.

Painted Jezebel (Delias hyparete)

 Sometimes only a small difference in angle can make a completely different photo. Notice this Painted Jezebel (Delias hyparete)

Common Parasol Dragonfly (Neurothemis fluctuans)


Common Parasol Dragonfly (Neurothemis fluctuans) right next to a small river

This fast flowing blackwater river is home to a special freshwater fish which is a popular aquarium fish. It was nice to finally see the biotope.

We found the Blue Dorsal Borneo Sucker (Gastromyzon ctenocephalus). This species grass on algae and other bio coatings of the rocks.

The species is diurnal and very active always feeding and moving around the boulders in the swift current. The water temperature here was 21 degrees C.

Above is a video of the Combhead Borneo Sucker Loach (Gastromyzon ctenocephalus) and the Blackline Algae Eater (Paracrossochilus vittatus) in their natural habitat.

Another species we found here was the Borneo dwarf pipefish (Doryichthys martensii). This species belong to the family of Pipefishes and seahorses (Syngnathidae). The largest specimens we found were around 10 cm TL.


We also found the Blue Dorsal Borneo Sucker (Gastromyzon ctenocephalus) in clearwater habitats like this. This is Sungai Sarawak Kanan at this location: 1°23'53.1"N 110°06'59.1"E

This male Blue Dorsal Borneo Sucker (Gastromyzon ctenocephalus) is in breeding condition. The depth here is only around 15 cm and the current is fast.

This is how this Blue Dorsal Borneo Sucker (Gastromyzon ctenocephalus) biotope looks from above.

This location is 1°32'23.1"N 110°08'45.8"E. We found many interesting species here.

Here is a pair of Blue Dorsal Borneo Sucker (Gastromyzon ctenocephalus) ready to spawn. The male (in front) was gently poking the female in and attempt to stimulate her.


The Sarawak loach (Nemacheilus saravacensis) feeds on fish and snail eggs, worms, insect larvae and small crustaceans. 

The color pattern of Sarawak loaches (Nemacheilus saravacensis) can vary and they can change colors instantly for camouflage. 

The Sarawak loach (Nemacheilus saravacensis) live in small groups often between 4-8 individuals. They seem very peaceful.  

Younger Sarawak loaches (Nemacheilus saravacensis) are often more pale likely for a better camouflage.

The Blackline Algae Eater (Paracrossochilus vittatus) seem to be a common fish in Sarawak. We found this species in most moderate and fast flowing rivers. They live in small groups and some are solitary.

I noticed that most of Blackline Algae Eater's (Paracrossochilus vittatus) had what seem to be wounds and scars on their nose. But I never observed any fighting. I am still not sure why the had the injuries.

But the solitary animals did not seem to have them. So perhaps the Blackline Algae Eater's (Paracrossochilus vittatus) harms each other during mating etc.

Both males and females of the Blackline Algae Eater (Paracrossochilus vittatus) seem to have this issue.

Only about 5 km from where the holotype was caught we found the Blue Tailed Borneo Sucker (Gastromyzon stellatus). This specimens was around 5 cm TL. Notice the 2 dark brown bars in the caudal fin. These are only visible when the fish is resting and fins are folded down.

Young specimens of the Blue Tailed Borneo Sucker (Gastromyzon stellatus) seem to have lighter colors but still the the blue caudal fin. This species seem rare in Sungai Sarawak Kanan compared to the other species in this river. I only observed less than 10 specimens. This specimen is around 3 cm TL.


I have not been able to identify this Jewel Orchid (Goodyera sp.). It might be new to science. Borneo have more than 1,700 species of orchids registered but no one really knows how many species are still hiding in the rainforest.

The Bornean Spotted Barb (Barbodes sealei), Bamboo shrimp (Atyopsis moluccensis) and the Greater scissortail (Rasbora caudimaculata) were all present here. This places is 1°36'46.4"N 110°12'10.5"E

Blue-throated Litter Skink (Sphenomorphus cyanolaemus) is very fast. This is the only photo I got of it before it disappeared.

In this clearwater river we found several freshwater fish species that we knew allready from the aquarium trade. 

 This video above shows Sarawak Rasbora (Rasbora sarawakensis) and 5-spot Barb (Barbodes sealei) in a clearwater river in Sarawak.

My friend wildlife photographer Dan Olsen gently bending a branch down with a large (around 20 cm) Giant Golden Orbweaver (Nephila pilipes) female. The males are less than 1 cm.

Wildlife photographer Dan Olsen.

Sarawak Rasbora (Rasbora sarawakensis) is a common freshwater fish in this state. It grows to around 5 cm TL and normally form small shoals in the fast flowing parts of the rivers.

The Sarawak Rasbora (Rasbora sarawakensis) seem to feed on detritus and insect larvae that drift with the current. 

The Bigmouth stream goby (Pseudogobiopsis oligactis) seem common in the rivers of Sarawak. I found them almost in every stream. They do not seem to eat algae even though I often noticed them biting into the brush algae and cyanobacteria on the bottom in a hunt for small fish fry and insect larvae.

Entering a merky habitat of an interesting small green tropical freshwater fish in Matang.

This video above shows the Jewel Island Danio (Sundadanio margarition) in the merky rainforest stream in Sarawak. These small fish (less than 2 cm) are difficult to see in this water full of organic particles but if you look carefully, you will see them.

This was the best photo I got of the Jewel Island Danio (Sundadanio margarition). I did not manage to do any interesting observations on this species due to the merky habitat.

In a small blackwater stream leading to the larger merky river we found Bako betta's (Betta ibanorum). The depth in this stream was around 15-20 cm.

The flow of this stream was relatively fast.

Even though this might not look like a fish biotope we found several interesting species here in this shallow swampy rainforest. Including the bright red Brown's betta (Betta brownorum) and one of the smallest fish in the world.

Meet the Sarawak pygmy cyprinid (Paedocypris micromegethes) one of the smallest vertebrates on the planet. Fully grown it is only around 1.2 cm. This is a male (on the right) and a female (in the middle).

Further in this flooded rainforest habitat we found the Clown Rasbora (Rasbora kalochroma). This dark blackwater biotope is like a large swamp area. I measured 25 degrees C here.

The video above shows the Clown Rasbora (Rasbora kalochroma) in its natural blackwater rainforest habitat of Sarawak, Borneo. 

Our amazing guide Michael Lo showing us the true Fiveband barb (Desmopuntius pentazona).

One of the largest predators here is the widespread Striped Snakehead (Channa striata). This species is found over most of South East Asia. It can grow up to around 100 cm TL.

The Striped Snakehead (Channa striata) is a bimodal breathing fish. It can breathe air at the water surface with a suprabranchial organ. This is a perfect adaptation during dry season, when water oxygen concentrations are reduced.

Small roads often lead to interesting places. 

The rain often reveils new and interesting species. But the visibility in the rivers makes it impossible take good photos and video. 

Batang Sadong

This is a male Rough Mabuya (Eutropis rudis). The type locality of this species of Sun Skink is Matang only around 80 km from This location 1°08'36.2"N 110°35'00.7"E in Serian.

The Rough Mabuya (Eutropis rudis) seem to feed mainly on flies, cockroaches and butterflies. They live up to their other common name Sun Skinks. I often observed them in the rainforest floor where rays of sun came through.

The Rough Mabuya (Eutropis rudis) are very nervous and often flee when approached by a photographer.

The wingspan of the Bornean Chocolate Pansy butterfly (Junonia iphita tosca) is around 6 cm.

The Serian Tractor Millipede (Phyodesmus magnificus) is one out of at least 37 species (8 genera and 3 tribes) of Tractor millipedes also called Platyrhacid Millipedes (Platyrhacidae) that exist on Borneo.

The Tropical carpenter bee (Xylocopa latipes) have amazing irrescent coloration in the wings in the right light.

This photo of the same Tropical carpenter bee (Xylocopa latipes) just in another light gave a completely different photo.

The Bornean straightline mapwing (Cyrestis nivalis borneensis) imitates a spider web.

The Green Land snail (Rhinocochlis nasuta) is the only member of its genus. A beautiful flattened snail.

This is an undescribed freshwater shrimp. The White Striped Long Arm Shrimp (Macrobrachium sp.) might be new to science but probably well known by the indigenous people. 

In this stream we found an interesting borneo sucker loach. The water temperature here was 22 degrees C. 

The Mixture Borneo Sucker Loach (Gastromyzon farragus) was described in 2006.

Above is a video of the Mixture Borneo Sucker Loach (Gastromyzon farragus) searching for food on the rocks in the fast current.

The Mixture Borneo Sucker Loach (Gastromyzon farragus) seem to feed mainly on diatoms.


The Mixture Borneo Sucker Loach (Gastromyzon farragus) is perfectly adapted to the fast current of the river. They use a minimum of energy because of their body shape and fins

The Mixture Borneo Sucker Loaches (Gastromyzon farragus) have a very distinct pattern.  

The Mixture Borneo Sucker Loach (Gastromyzon farragus) is vulnerable due to habitat loss and pollution.

In this stream we found Bogners Buce Plants (Bucephalandra bogneri) on the rocks. This species is hardy and many aquarist knows this genus of plants to be easy to keep in the aquarium hobby.

The Bogners Buce plant (Bucephalandra bogneri) belong to the family Araceae and the subfamily Aroideae. In this subfamily you will find other known aquarium plants like Anubias, Cryptocoryne and Pistia.

Bogners Buce Plant (Bucephalandra bogneri) has adapted to the shifting water levels of the river. The roots grow on to the rocks and the plant can withstand the pressure of extremly fast flow. The plant grow both emerged and submerged.

Bogners Buce plant (Bucephalandra bogneri) does not seem to need much light. They grow in rainforest streams and rivers where trees are covering the habitat. So only a few sun rays break through once in a while.

Here we also found the Blackline Algae Eater (Paracrossochilus vittatus)

I also observed some tadpoles which reminded me of the family of South American Armored Catfishes (Loricariidae).

The tadpoles are a competitor to the Mixture Borneo Sucker Loaches (Gastromyzon farragus) as these also feed mainly on diatoms. 

Bornean Malay Cruiser (Vindula dejone dajakorum), Sarawak Brookes Birdwing (Trogonoptera brookiana brookiana) and Bornean Common Grass Yellow (Eurema hecabe latilimbata) all these butterflies attracted to a burned out bonfire. They are feeding on the minerals released from the ash.

Some Bornean Common Grass Yellow Butterflies (Eurema hecabe latilimbata).

For comparison the Bornean Common Grass Yellow Butterflies (Eurema hecabe latilimbata) and Bornean Malay Cruiser butterfly (Vindula dejone dajakorum)

The Sarawak Brookes Birdwing (Trogonoptera brookiana brookiana) is a large butterfly species with a wingspan of up to 17 cm. This species is truly amazing. This subspecies was the first to be described in 1855.

 Sarawak Brookes Birdwing (Trogonoptera brookiana brookiana)

Sarawak Brookes Birdwing (Trogonoptera brookiana brookiana)

This might be the Rough Seedsplashers Plant (Piptospatha impolita). This species spread its seeds with the river as the name suggests.

Semenggoh Nature Reserve


In Siburan we visited this amazing place where we found the Bornean Keeled Green Pit Viper (Tropidolaemus subannulatus).

The Bornean Keeled Green Pit Viper (Tropidolaemus subannulatus) is a venomous snake. It is not aggressive in any way.

The camouflage of the Bornean Keeled Green Pit Viper (Tropidolaemus subannulatus) is perfect as you can see in this Red Button Ginger (Costus woodsonii).

The Iconic Bornean orangutan (Pongo pygmaeus) is one of the 4 species of Orangutans. The first orangutan lived in Vietnam and was extinct more than 12.000 years ago. Now the 3 species left are all Critical Endangered due to habitat loss.

In this nature reserve the habitat and wildlife is protected and the Northwest Bornean orangutan (Pongo pygmaeus pygmaeus) is safe here. The name Orang utan means "Man of the forest" and it is not far from the truth. This primate shares 97% of their DNA with us. 

The Northwest Bornean orangutan (Pongo pygmaeus pygmaeus) is a fruit-eater (Frugivores) with 60-80% of the diet consisting of fruits. This females was right next to where we parked our car.


 At first glance the nest of the Northwest Bornean orangutan (Pongo pygmaeus pygmaeus) look likes an open bird nest in the highest trees.

Close up you will see a nest that can withstand an 100 kilo Northwest Bornean orangutan (Pongo pygmaeus pygmaeus). An average male weigh 75 kilos and a female around 40 kilos but males up to 100 kilos have been observed.

The arms of the Northwest Bornean orangutan (Pongo pygmaeus pygmaeus) is longer than they seem. They can reach 1.5 meter.

Currently the Northwest Bornean orangutan (Pongo pygmaeus pygmaeus) is one of 3 subspecies recognized on Borneo-

The Northwest Bornean orangutan (Pongo pygmaeus pygmaeus) belong to the only genus of great apes native to Asia. This species is endemic to Borneo. This specimen was very calm and easy to get close to.

The Malesia Stick Insect (Parorthomeria alexis) is endemic to Borneo. We usually found this species on large leafes of different plants species.

Niah National Park

The Sungai Niah is a river you have to cross to get to the amazing giant cave Niah.

The Niah Cave Scorpion (Lychas hosei) consuming a cave cricket.

Niah cave is home to several species of bats. One of them is the Fawn Roundleaf Bat (Hipposideros cervinus).

A common plant species in this national park is the Variegated Croton (Codiaeum variegatum).

The Variegated Croton (Codiaeum variegatum) is a common house plant in many countries.

The Pale Giant Squirrel (Ratufa affinis) is considered Near Threatened (NT) by the IUCN. 

Front view of the Fanged Pitcher Plant (Nepenthes bicalcarata). On the edge of the pitcher opening you can see some lines, these are called ribs. They two rows of spines which run down the cup is called wings.

Back view of the Fanged Pitcher Plant (Nepenthes bicalcarata). This species is actually the largest of the genus. It can grow more than 20 meters high and the stem can be up to 3,5 cm i diameter.

The Sarawak Stick Grasshopper (Erucius sarawakensis) lives in the rainforest around Niah cave.

The Variable Sentinel (Orchithemis pulcherrima) a common dragonfly in this area. 

The Red Land Snail (Coptocheilus anostomus) are found in and outside the cave.

The Black Kneed Malaysian Assassin Bug (Velinus nigrigenu) is common in this region. The family of Assasin bugs (Reduviidae) contains around 7000 species worldwide.

Lambir Hills National Park

Clearwater stream in Lambir Hills in Sarawak. Lambir Hills National park have the highest diversity of trees in all of Borneo. More than 1,175 tree species were found in only 52 hectares (0.52 km2).

Wildlife photographer Dan Olsen recording the behaviour of the freshwater fish called Akar betta (Betta akarensis) near a waterfall in Lambir Hills

The underwater view of the same habitat in this small pool which contained many interesting freshwater fish and shrimps species.

A male Akar betta (Betta akarensis) in its natural habitat. 

This female Akar betta (Betta akarensis) is very curious and kept following the camera. The water temperature here was 23 degrees C.

An empty exoskeleton of a Bornean Cicadas (Chremistica borneensis). This species live underground for seven years as a nymph they crawl up a tree and sheds the exoskeleton.

This shallow stream was hiding another interesting species endemic to the area. 

Another interesting species we found in large schools here in Lambir Hills was the Pelvic Striped Rasbora (Rasbora tubbi). This large mouthed species seem to feed mainly on fish fry and insects.

A pool from a waterfall in Lambir Hills.

This small stream is a habitat of the Bornean Tiger Barb (Puntigrus anchisporus). We did not catch any. In the video below you can see what we found here.

 The video above shows a small stream which runs through some fields and is home to the Borneo Halfbeak (Dermogenys collettei), the 5-spot Barb (Barbodes sealei) and Spotted barb (Barbodes banksi) and Silver Rasbora (Rasbora argyrotaenia).  

A bush katydids or leaf katydids (Phaneropterinae) landed on our side mirror. This subfamily (Phaneropterinae) of insects within the family Tettigoniidae contains over 2000 species in 85 genera.

 I have not been able to identify this species. It does look like the Bush cricket (Caedicia simplex) native to New Zealand and this species have been registrered in Sabah, Borneo but this is probably a misidentification.


Close to the border of Brunei Darussalam in the affluents of Baram river we were looking for a very special freshwater fish. The habitat was suppose to look like this.

The species we were looking for should live in both blackwater and clearwater habitat and our guide had planned to take us to a very beautiful location where he had been many times before.


Sadly this amazing area had been destroyed. This habitat is now gone. The demand for palm oil is still rising. More and more rainforest is being burned down and the land is used for crops. The bio diversity in such plantations is only a small fraction of what lives in a rainforest.   

The fires are suffocating most wildlife. The water surface was covered in soot, which made it impossible for the fish to retain oxygen even the fish species that normally breathe through the surface. I threw a stick into the stream to break through the soot. 

As soon as the soot was dissolved and the sureface was clear again the fish swam fast up to breathe. This rainforest was home to the Spotfin Betta (Betta macrostoma) and many other species.


On the other side of the road we found a stream with less soot and silt. Here the rainforest was still relatively intact but off course still marked by the deforestation near by. We could observe and document the habitat and their behavior here.


This male Spotfin Betta (Betta macrostoma) was very curious about our work. The species name: macrostoma meaning: big mouth fits perfectly as you can see in this photo. Water temperature here was 25 degrees C.

Bako National Park

Bako national park is an important sanctuary for the wildlife near Kuching. This area is only 27 km2 but protects many thousands of species of animals and plants.

 Common Water Monitor (Varanus salvator) in the mangrove of Bako National Park, Sarawak near Kuching.

The water levels in the mangrove rises and falls with the tide four times a day. Some fish have adapted to this daily circle in an amazing way. A fish that walks on land.

Boddart's goggle-eyed goby (Boleophthalmus boddarti) is a species of mudskipper which can grow to about 22 cm TL. They feed on algae, crustaceans, small insects, worms and eggs from fish and snails.

When the water rises in the mangrove fish from the sea arrive in search for food in the flooded forest.

I could only find three species of jellyfish recorded in Sarawak The white jellyfish (Lobonema smithii), the red jellyfish (Rhopilema esculenta) and the spotted jellyfish (Mastigias papua) but this one does not key out to any of these species. The diameter of this jellyfish was around 70 cm.


In a blackwater habitat we found the vulnerable Bako betta (Betta ibanorum). I observed them eating mosquito larvae in the surface. 

The male Bako betta (Betta ibanorum) has an elongated dorsal fin which seem to work as an optical illusion during their mating display. Notice the fluorescent blue tip which in this blackwater biotope does not look like its connected to the rest of this dorsal fin. 

This Bako betta (Betta ibanorum) habitat did not have any underwater plants. We only found emerged aquatic plants in this stream.

The Bako betta (Betta ibanorum) is an interesting species which seem to shoaling in these small blackwater stream. I have not seen this behavior in that many other Betta species.  

The Bako Betta (Betta ibanorum) habitat above the surface.

The Bako betta's (Betta ibanorum) in this stream were very curious. It was almost impossible to get a photo without them being too close to the camera.

Only a few rays of sunlight penetrated the surface. So from above this Bako betta (Betta ibanorum) biotope looked extremely dark.

Fully grown the Bako betta (Betta ibanorum) males are around 10 cm TL and they seem to accept each others presence even under these very small conditions.

A short video of the Bako betta (Betta ibanorum) in this habitat. Music by Morten K. Holm Hansen song: Atlas Moth

A sunset and the view of Kampung Budaya Sarawak from the Bornean rainforest.

The sunsets here were amazing and off course a photograph will never capture the fantastic display of colors.

 As you can see on this photo it's easy to spot scorpions if you bring UV torches. This is the Asian forest scorpion (Heterometrus longimanus). One of the largest scorpions in the world. This specimen was 15 cm.

The coast line here have lots of mudskippers, hermit crabs but look out for saltwater crocodiles one of the only dangerous elements here. The water is merky so you might see them too late. Be careful. 

Borneo has many carnivorous plants with pitfall traps (Pitcher plants). These traps are formed by specialized leaves which contain a cavity of digestive liquid. This is the Slender Pitcher Plant (Nepenthes gracilis).


Like the other species the Slender Pitcher Plant (Nepenthes gracilis) attract and drown their prey with their nectar. As you can see in the two photos above, they can look very different. These are both upper pitchers.

Closer to the ground they have their lower pitchers. They look very different. This is lower pitchers of the Slender Pitcher Plant (Nepenthes gracilis). The two type of pitchers attracts different prey.

This is Raffles pitcher plant (Nepenthes rafflesiana). The largest pitchers we observed in this species was around 20 cm long but it should be able to exceed impressive 35 cm in lenght with a width of 15 cm.

The lid of the pitchers work as a roof. Without a lid the digestive liquid would evaporate in the sun or diluted during heavy rain. But the lid also works as a trapping mecanism. When raindrops hit the lid, prey is often catapulted into to cup. Above you see the extreme variable Raffles pitcher plant (Nepenthes rafflesiana).


This clearwater river was in the shade of the rainforest above and only a few sun rays came down through the canopy.

In between these rocks I found a species that I had never seen before.

Bornean dwarf spiny eel (Macrognathus keithi) is less than 25 cm TL when fully adult. This species seem to feed mainly on fish fry, fish eggs, insect larvae and worms.

Sungai Stunggang

In this biotope we found Croaking gourami (Trichopsis vittata).

The Croaking gourami (Trichopsis vittata) seem to be a very hardy species. Even though this area was being dug up and the water was full of silt, this species still seem to thrive and we found great numbers of them.

The Croaking gourami (Trichopsis vittata) male builds a nest of bubbles in the water surface for the eggs to hatch in. This way they are closer to the oxygen-rich surface.

I prefer underwater photos, but in some biotopes the water is not clear enough for underwater shots. So I bring a small photo aquarium. Here I placed a pair of Croaking gourami (Trichopsis vittata) from the habitat in the background.

Large areas in this swampy area is covered in the aquatic plant Waterthyme (Hydrilla verticillata).

A young Forest Snakehead (Channa lucius) from the same habitat.

I have not been able to identify this species of wasp. It was resting on a rock next to the river.

Above is a map of the places we visited on this trip


A special thanks to:

Dan Olsen

Michael Lo

Henrik Bringsøe (Reptilia)

Daisy Wowor (Palaemonidae)

David Boertmann (Hygrophoraceae)

Bucephalandra sp. "Wavy green" (Photo by Dan Olsen


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Wildlife in and around the river system

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