Amazon, Rio Negro

122nd place in Biotope Aquarium Design Contest 2018

croatia Turkey. Zafer Işık

Volume: 230 L
Dimensions: 130х40х45 cm
List of fishes: Hemigrammus bleheri, Paracheirodon axelrodi
List of plants: Sagittaria subulata, Cabomba aquatica, Vallisneria spiralis
Description of decorations: The stones, sand and driftwood in the aquarium were collected from nature and have been used for a long time.
Description of equipment: Lifetech 835 external filter, Unistar 2L internal filter, LED lighting.
Water parameters: Temperature is 28°C, pH is 6.


Description of the area surrounding the biotope: The Rio Negro (Black River in Spanish) is the largest tributary of the Amazon river. It is also the largest ‘blackwater’ river in the world. The river can be studied In three sections, ‘the upper, middle and lower course’. The river originates in Colombia, flowing east passing through settlements. The river here in Colombia is known as the Guainia River. After the river flows on it turns south-west where its then referred to as the ‘Rio Negro’. Uaupes river is the largest tributary of the Rio Negro, it joins it near Sao Joaquim. The river then continues east as the Lower course. During the wet seasons, this river is responsible for floods in the surrounding areas. This forms the main upper part of the river. The Middle course continues into Venezuela. The river is fed on both sides with tributaries and grows in size creating river islands, which is a common feature of all rivers in the Amazon basin. The river is a succession of lagoons and channels during this season. Blackwater streams, pools are often seen. The river runs through rainforests, thus collecting numerous fallen branches of trees and lots of leaves that fall. The banks are often deposited with fine sand.

Description of the underwater landscape of the biotope: The blackwater of the river is a result of the tannin-stained, tea coloured water. This is due to the slow moving waters in which decaying vegetation, roots, wood etc result in leeching of acids. The water is transparent and “tea coloured”. The base is typically lots of leaf litter, which covers the bottom of fine white sand and sometimes clay.

Description of the parameters of the habitat: The water is very transparent. Tea coloured, tannin-leeched water. Water hardness is almost negligible. The average temperature is always between 27-30°C. The pH is very low and acidic often as low as 4, but an average range of 4.5-6.

List of fishes and invertebrates occurring in the nature biotope: Hemigrammus bleheri, Paracheirodon axelrodi.

List of plants found in the nature biotope: Sagittaria subulata, Cabomba aquatica, Vallisneria spiralis.

Sources of information:,

Comments of the members of the jury of Biotope Aquarium Design Contest 2018