Flooded Banks of Rio Nanay, Peru During Rainy Season

_th place in Biotope Aquarium Design Contest 2020

Volume: 400 L
Dimensions: 150 x 60 x 45
List of fishes: Pterophyllum scalare, Nannostomus eques, Petitella georgiae, Pseudohemiodon apithanos, Corydoras loretoensis
List of plants: Helanthium tenellum, Pistia stratiotes
Description of decorations: White sand was used as a substrate which closely resembled that of the Rio Nanay, the hardscape was created by attaching oak branches and pieces of root to an eggcrate frame. This allows fish to swim freely through and underneath the structure, allowing Corydoras to spend the day time resting in the shadows. The finer roots are willow roots collected from a felled tree at a nearby river. The Helanthium tenellum was grown on the hardscape using a hydroponic matting to keep it attached. In this aquarium I have tried to recreate the impression of a fallen tree at the banks of the Nanay, with branches growing up and out of the water and roots hanging into the water below. Helanthium tenellum grows at the banks of the river and has been submerged by flood waters. The aim was to create a niche for each of the inhabitants, a sandy bottom for the Corydoras and Pseudohemiodon, roots and branches to allow the Angels to occupy territories and spawning sites and floating plants and roots to create a safe microhabitat for the pencilfish and tetras.
Description of equipment: Lighting: 2 x Kessil Tuna Sun A160, Heating 2 x TMC 300W heater, Filtration: Custom sump with Biohome media and filter floss
Pump: Abyzz A100, CO2 injection via CO2 Art regulator and fire extinguisher, Fertilisers: TMC dosing pump with EA Aquascaper complete fertiliser
Water parameters: Water temperature is 27C pH is 5.8 and gH is 2-3. Water is mixed from RO and tap water and then remineralised with prodiscus mineral and Phophoric acid.
Additional info: 70% water changes are carried out weekly with remineralised RO which is heated to tank temperature to avoid shock.


Description of the area surrounding the biotope: The Nanay is a tributary of the Amazon in Northern Peru running entirely through the lowlands. It is crooked and has a slow current dividing into many canos and lagoons flooding the flat, low areas on either side of its banks. The Nanay is a black water river, stained by tannins from the surrounding secondary forests with trees like ceticos, cataguas, and chontas lining its banks. During the rainy season, the river spills over its banks, flooding the nearby forest, causing these trees to collapse and fall into into the water. This tangle of fallen branches and roots creates habitat for huge numbers of smaller fish.
Description of the underwater landscape of the biotope: The Nanay passes through areas of secondary rainforest before draining into the Amazon. The substrate is entirely composed of white sand and large rocks are absent. Visibility is poor due to turbidity and dark staining from tannins and humic Acids. Aquatic plants are scarce although during the rainy season, marginal vegetation becomes submerged for months at a time, floating plants such as Pistia are present in huge numbers with hanging roots creating a haven for smaller fish. Fallen branches and leaf litter form much of the underwater landscape, with tangles of roots creating spawning habitat for Angels and Discus.
Description of the parameters of the habitat: PH 5.2/5.5 – Conductivity: 40/50 microSiemens/cm T: 26-30 °C.
List of fishes and invertebrates occurring in the nature biotope: Mesonauta festivus, cichla sp, Symphysodon aequifasciatus, copella arnoldi, Nannostumus trifasciata, N. mortenthalleri, Hyphessobrycon margitae, Hyphessobrycon bentosi, Apistogramma bitaeniata, Corydoras atropersonatus, Hyphessobrycon erythrostigma,
List of plants found in the nature biotope: Plants re scarce in this habitat but floating plants such as Pistia stratioites can be found in large numbers. Ehinodorus grisebachi can also be found and was historically grown here for the aquarium trade.

Threats to the ecology: Deforestation to clear land for palm tree plantations and pollution resulting from anthropogenic activities in land such as fertiliser and herbicide use.

Sources of information:

  1. http://forum.simplydiscus.com/showthread.php?26263-Rio-Nanay-Biotope
  2. https://www.fishbase.se/country/CountryChecklist.php?what=list&trpp=50&c_code=604&csub_code=&sortby=alpha2&ext_CL=on&ext_pic=on&vhabitat=fresh
  3. http://www.tomc.no/fish.aspx?fishIndexID=2286&gruppeID=1
  4. http://www.aquatechnics.net/nanay.htm

Comments of the members of the jury of Biotope Aquarium Design Contest 2020