Creek in the flooded forest in Paraná Ataú, Brazil

_st place in Biotope Aquarium Design Contest 2022

Volume of aquarium: 240

Dimensions of aquarium: 120x40x50 cm

List of fishes: Ivanacara adoketa, Crenicichla regani, Moenkhausia sp. (collettii or copei)

List of plants: N/A

Description of Decorations and Substrate: Substrate: natural beige sand 0.1-0.3 mm, bought in the local zoo shop.

The mix of catappa, banana tree, and mostly jackfruit tree leaves covers most part of the substrate as it is in a natural biotope. A few small pods provide hiding places for fishes and also do not stand out from the natural habitat. One big dry leaf of unknown palm.

Plenty of birch twigs which were collected in a local park approximately a half year ago. Initialy, birch does not look like a suitable tree for the Rio Negro biotope aquarium, but over time, most of them begin to become covered with algae and become very similar to branches from many underwater videos from the Rio Negro. There are 2 medium-size driftwoods (probably mangrove) which are also slightly covered with algae and leaves.

Description of Equipment: External filter: Aquael Ultra 1400
Lighting: 1×16,3 Watt Eheim classicLED daylight (6500k)
Heater: Eheim thermocontrol 150

Osmosis system for water changes: Osmotech Professional 150 GPD

Water Parameters: Temperature: 25-26°C
PH: 5.5
TDS: 40 mg/L
GH/KH: < 1

Additional Info: Normally, around 15-20% of the water is changed every week with pure RO/DI osmosis water and adding a couple of new cappa leaves for keeping PH on a moderately low level.

Also on the video you can see how changeable the color of Ivanacara adoketa is. Some of the shots were made before spawning, where they are in full glory, and some after an unsuccessful spawning, where they are in a stressful color.

Aquarium video:

Description of the Area Surrounding the Biotope: Paraná Ataú is a group of small forest streams in Rio Negro, the largest tributary of the Amazon River. It’s located near the bottom part of the Rio Preto, which is one of the affluents of the Rio Negro. Probably because it’s located not so close to Barcelos, which is an important place for the ornamental fish export industry, there is still not as much information about this biotope as from other places near Barcelos, like Igarapé Daracuá. Nevertheless, this area looks like a dense forest with lots of vegetation that is flooded by the river in the rainy season, so the only way to get to this area is by boat.

Description of the Underwater Landscape of the Biotope: The typical landscape of this area looks like slowly to medium moving blackwater streams. Due to a lot of organic, humic acids or compounds in the water, it’s tea-colored, depending on the season it may have a different brightness of the color from slightly yellowish to dark brown. The depth of the water also depends a lot on the season which is lower in the dry season and obviously higher in the rainy season, but the flooded forest areas might have a depth around a couple of meters. The substrate in this area is bright sand that has a small grain size and is mostly covered with red-brownish leaf litters. Apart from the countless amount of leaves, in the bottom part of the landscape, there are a lot of branches, driftwoods, and sprouts of young plants in the flood season. All of them provide plenty of hiding places that attract the small inhabitants of this area, so naturally, the bottom is full of snorkeling dwarf cichlids like Crenicara punctulata, dwarf Crenicichlas (regani or notophthalmus), Apistogramma sp., and others. Of course, there are also a lot of Paracheirodon axelrodi here as one of the most popular tetras in Rio Negro. The middle-top part of the water is saturated by other small “piabas” like Moenkhausia sp. and Hemigrammus sp, and bigger cichlids like Crenicichla sp., Pterophyllum leopoldi, Heros notatus. In the flooded forest area, it also may contain hanging leaves or branches from flooded trees, such as the palm leaves as in the featured aquarium.

Description of the Habitat Parameters: Unfortunately, there are no measurements from Paraná Ataú, but as a matter of the fact that this place is part of the Rio Negro basin, most probably the water parameters are the same. The water in the Rio Negro is famous for consisting of a super low amount of mineral content that makes its conductivity is very low (around 17.0 ± 15.2 S/cm) and solute-poor (TDS here is 7.1 ± 6.7 mg/l). The parameters of the water depend on the season, but in general, it’s extremely acidic and has pH around 4.5 ± 0.9. During the dry season the temperature might be quite high due to the dark coloration of the water, it absorbs more solar radiation than clear-water rivers, so might exceed 28-29°C. In the rainy season it calms down up to 23-24°C.

List of Fishes and Invertebrates Occurring in the Nature Biotope: Dicrocuss filamentous
Crenicara punctulata
Crenicichla regani
Crenicichla notophthalmus
Hemigrammus bellotti
Hemigrammus analis
Hemigrammus coeruleus
Heros notatus
Moenkhausia collettii
Laetacara thayeri
Ivanacara adoketa
Paracheirodon axelrodi
Pterophyllum leopoldi

List of Plants Found in the Nature Biotope: Due to extreme conditions such as super acidic water and lack of light due to the color of the water, aquatic plants are not found in this location.

Threats to the Ecology of the Biotope: Obvously, it’s super important for us to look after the health of Rainforests, because it’s the unique system that is also calling as ‘lungs’ of the planet, which is the super importnat nowadays when the ecological situation in the Earth is quite bad due to the climate change and the amount of emissions.

But not everyone knows that our hobby can help save rainforests. Some studies show that due to the low demand for wild fish imported from Rio Negro, local fishermen leave their jobs and start working in logging or cattle breeding, which often has a much more detrimental effect on the ecology of these places. In addition, the population of wild fish in Rio Negro is sustainable, plus, unfortunately, one way or another, most of them still die in the dry season, so they can find a new life in home aquariums.

2 out of 3 species in the shown aquarium are wild fishes from Brazil (Moenkhausia sp. and Crenicicla regani). Of course, wildcaught fishes are usually more difficult than local breeded, because they require the special adoption to the local water and more strict rules regarding the quarantine, but I believe that buying these wildcaught fishes we at least may try to help the ecology of this region.

Sources of Information: