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Bensbach Creek, Western Province, Papua New Guinea
Papua New Guinea, Western Province, North Fly District
The small blackwater tributaries of the Upper Fly River near Kiunga, Western Province, Papua New Guinea, are among the region’s most biologically rich freshwater habitats. These slow-flowing rainforest streams are characterised by soft, acidic, tannin-stained water, sandy substrates covered with leaf litter, submerged roots, and dense riparian vegetation providing continuous shade.
Seasonal rainfall influences water levels and connectivity between creeks and floodplain wetlands, creating suitable conditions for a diverse assemblage of freshwater fishes and aquatic invertebrates.
These streams represent the natural habitat of Pseudomugil paskai (Paska’s Blue-eye), a small rainbowfish renowned for its vibrant coloration and peaceful behaviour. This aquarium recreates the physical structure, water chemistry, and ecological characteristics of these pristine rainforest creeks, faithfully representing one of Papua New Guinea’s unique blackwater ecosystems.
- Submitted by
- Shivansh Rajpoot
- Approved by
- Heok Hee Ng & Greg Martin
- GPS
- -6.0475421, 141.1083527
- Geographical region
- Oceania
- Drainage Basin
- Gulf of Papua
- River catchment
- Upper Fly River
- Water body type
- River
- Water body name
- Small Blackwater Creek
- Water body part
- Open water
- Water body course
- Upper course
- Water body: tributary of
- Tributary name
Videos above and below water
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Water Chemistry
Water information
- Water type
- Freshwater
- Water color
- Black water
- Water transparency
- Low
- Concentration of sediments
- Low
- Water temperature
- 26 °C
- Water flow/curent
- Slow
Chemical parameters
- pH
- 4.8
- Conductivity
- 60
- GH
- dGH
- 2 °dGH
- KH
- dKH
- 1 °dKH
- Dissolved Oxygen
- 90 %
Substrate in nature
- Sand
- Beige
- Pebble/Gravel
- None
- Stone
- Brown
- Stone form
- Roundish
- Silt/Mud
- None
- Leaves
- Adundant
- Driftwood
- Many
- Submerged terrestrial vegetation
- Yes
Aquatic Biotope
- Date of collecting
- Collecting area
- River bank
- Water depth
- Air temperature
- 24 °C
- Sunlight
- Partial shade
Environment
- Environment
- Untouched
- Surrounding area
The Upper Fly-Bensbach region of Western Province, Papua New Guinea, is characterised by extensive lowland tropical rainforest, seasonally flooded forests, and freshwater swamp ecosystems. Small blackwater creeks meander through dense vegetation, where towering rainforest trees, pandanus, sago palms, and riparian shrubs form a closed canopy that shades the water throughout the day.
The region experiences a humid equatorial climate, with annual rainfall exceeding 2.500mm and relatively stable temperatures ranging from 24-30°C. Organic matter from the surrounding vegetation continuously enters these creeks, creating tannin-rich blackwater habitats that support a remarkable diversity of freshwater fishes, crustaceans, aquatic insects, amphibians, and birds.
- Underwater landscape
The habitat consists of slow-flowing, tea-coloured blackwater streams with high water clarity despite their dark appearance. The substrate is primarily composed of fine sand covered with leaf litter, decomposing branches, submerged roots, and occasional fallen logs.
Dense riparian vegetation provides shelter and limits light penetration, while marginal aquatic plants occur in more open sections of the creek. Pseudomugil paskai inhabits these quiet waters together with other native fishes, gudgeons, freshwater shrimp, and aquatic invertebrates, using submerged roots and woody debris for shelter, feeding, and spawning.
Aquatic inhabitants
- Pseudomugil paskai (Pseudomugilidae) – Paska’s Blue-eye – Common
- Mogurnda sp. (Eleotridae) – Sleeper Goby – Occasional
- Giuris margaritacea (Eleotridae) – Snakehead Gudgeon – Occasional
- Caridina sp. (Atyidae) – Freshwater Shrimp – Common
Aquatic vegetation
- Cryptocoryne sp. (Araceae) – Crypt – Rare
- Cyperus sp. (Cyperaceae) – Sedge – Common
- Threats to ecology
Although much of the region remains relatively undisturbed, increasing pressures from logging, agricultural expansion, mining activities, road construction, and wetland drainage threaten the integrity of these blackwater ecosystems. Sedimentation, habitat fragmentation, and declining water quality may alter the delicate environmental conditions required by native freshwater species.
Conserving intact rainforest catchments and maintaining natural hydrological processes are essential for protecting the unique biodiversity of the Upper Fly-Bensbach freshwater ecosystems and the specialised species they support.
Riparian zone
- Trees near the aquatic habitat
-
Many - Pandanus julianettii (Pandanaceae) – Karuka Nut Palm
- Trees near the aquatic habitat
-
Many - Melaleuca cajuputi (Myrtaceae) – Cajuput Tree
- Trees near the aquatic habitat
-
Many - Metroxylon sagu (Arecaceae) – Sago Palm
- Trees near the aquatic habitat
-
Many - Nauclea orientalis (Rubiaceae) – Leichhardt Tree / Yellow Cheesewood
Bibliography
-
T.F.H. Publications - Rainbowfishes of Australia and Papua New Guinea
by Allen, G.R. & Cross, N.J.
ISBN 978-0866228788
-
Christensen Research Institute - Field Guide to the Freshwater Fishes of New Guinea
by Allen, G.R.
ISBN 978-0958125506
-
Aquatic Photographics - Rainbowfishes: Their Identification, Care & Breeding
by Allen, G.R., Unmack, P.J. & Hadiaty, R.K.
ISBN 978-0975150222
-
T.F.H. Publications - Freshwater Fishes of Australia
by Allen, G.R.
ISBN 978-0866229426
-
Christensen Research Institute - The Freshwater Fishes of Papua New Guinea
by Allen, G.R.
ISBN 978-0958125520
Comment by the expert
Heok Hee Ng: Description is OK, but video provided is not that relevant in showcasing the aquatic habitat.
Greg Martin: The supplied video didn’t show any underwater footage. Points deducted for this.
