Shallow blackwater habitat in the middle Rio Negro

69th place in Biotope Aquarium Design Contest 2017

United_Kingdom United Kingdom. James Sheen

Volume: 240 L
Dimensions: 121x41x55 cm
List of fishes:  Paracheirodon axelrodi, Nannostomus eques and Dicrossus filamentosus
List of plants: N/A
Description of decorations:  I have used playsand to recreate the sandy substrate of the area, the leaf litter bed has been achieved using Dried Magnolia leaves which also includes various seed pods that are found in the area.  Various sections of Redmoor root and Manzanita wood has been used to create the look of a root system. I have added some terrestrial twigs with green leaves on to replicate the terrestrial plants that are submerged during the wet season.
Description of equipment:  Fluval 406 External filter and Dennerle Trocal LED 40 18W
Water parameters: Temperature is 24°C and pH is 7.6

Description of the area surrounding the biotope: In the shallows of a small area of flooded forest not far from the city of Barcelos, in the Amazonas state, Brazil. The igarape is near the village of Daracua, about a day upriver from Barcelos. It’s a representative of a wide range of shallow, blackwater habitats found throughout the Amazon and its tributaries, especially the Rio Negro in Brazil and the Orinoco in Colombia and Venezuela. The area is flooded during the wet season and when underwater a mass of leaf litter that was previously on the forest floor is now home to many fishes, creating hiding places and items to graze on.

Description of the underwater landscape of the biotope:  It is rich in tannic and humic acids, both of which contribute to the characteristic dark brown colouration of the water. The water also carries a lot of particulate organic matter, which makes a food source for many fish and invertebrates. Lots of fallen branches, bark, seed pods, and a deep carpet of leaf litter line the bottom in areas close to the water’s edge, providing lots of shelter and places to hide but also a great source of detritus and biofilm for fish to graze on.

Description of the parameters of the habitat: The water temperature is 82-86F/28-30C, extremely acidic (as low as 3.5 pH in this particular habitat).

List of fishes: Paracheirodon axelrodi, Nannostomus unifasciatus, Nannostomus eques, Bryconops sp., Hemigrammus sp., Aequidens tetramerus, Hemigrammus bellotti, Dicrossus filamentosus, Amblydoras sp. and Apistogramma gephyra.

List of plants: Myriophyllum sp.

Threats to the ecology: The area remains largely intact and protected in no small part due to the aquarium trade which provides a livelihood for hundreds of families living in the region. Without the cash incomes provided by collecting fish (a low environmental impact activity), many would likely turn to slash-and-burn agriculture, illegal timber trade, or cattle ranching for income – all of which are much more detrimental to the forests and surrounding waterways.

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