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#10491 Igarapé Tucano, Rio Negro, Brazil

Brazil, Amazonas

This aquarium recreates a blackwater igarapé (small forest stream) from the Rio Negro basin in the Brazilian Amazon. These habitats are characterized by submerged tree roots, fallen branches, leaf litter, and tannin-stained water, which gives the environment its dark amber coloration. The Rio Negro is the world’s largest blackwater river and is renowned for its extremely soft, acidic water and remarkable biodiversity.

Submitted by: Luis Sequeira

GPS: 0.1134720, -67.8332214

Geographical region: South America
Drainage Basin: Rio Amazonas
River catchment: Rio Negro
Water body type: Igarapè
Water body name: Tucano
Water body part: Pool
Water body course: Lower course
Water body: tributary of: Rio
Tributary name: Negro

Videos above and below water

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Water Chemistry

Water information

Water type: Freshwater
Water color: Black water
Water transparency: Medium
Concentration of sediments: High
Water temperature: 26 °C
Water flow/curent: Slow

Chemical parameters

pH: 6.0
Conductivity: 30
GH: 10 mg/l
dGH
KH: 7 mg/l
dKH
Dissolved Oxygen: 70 %

Substrate in nature

Sand: White
Pebble/Gravel: None
Stone: Grey
Stone form: Roundish
Silt/Mud: Beige
Leaves: Adundant
Driftwood: Many
Submerged terrestrial vegetation: None

Aquatic Biotope

Date of collecting: 11/13/2025
Collecting area: Small bay
Water depth: 1,0m
Air temperature: 28 °C
Sunlight: Partial shade

Environment

Environment

Untouched

Surrounding area

The river is surrounded by dense tropical rainforest with abundant riparian vegetation. Large trees line the banks, creating a shaded environment and allowing only filtered sunlight to reach the water. Exposed roots, fallen branches, and leaf litter are common along the shoreline, contributing organic matter to the ecosystem. The watercourse flows slowly through the forest, providing shelter and breeding areas for many fish, invertebrates, birds, and other wildlife. This type of habitat is characteristic of Amazonian blackwater streams and igarapés.

Underwater landscape

Below the water surface, the streambed is composed mainly of fine sand covered with leaf litter, small branches, and submerged wood. Fallen roots and tree limbs create a complex underwater structure that provides shelter, feeding grounds, and spawning sites for fish and invertebrates. The water is clear to tea-colored due to tannins released from decomposing organic matter. Aquatic vegetation is scarce, while the substrate and woody debris dominate the habitat, creating a typical Amazonian blackwater stream environment.

Fish:

Paracheirodon axelrodi (Characidae)

Threats to ecology

The main ecological threats are deforestation, mining, water pollution, climate change, and habitat degradation. These activities can alter water quality, reduce forest cover, and threaten the survival of native species adapted to blackwater habitats.