Authentic Biotope Aquarium

Malebo Pool Habitat, Congo

Habitat: An open water-and riverbank in the Malebo Pool, Congo River.  With a length of almost 5000 km, the Congo River is the second longest river in Africa (after the Nile River) and the eighth longest on earth.  It carries murky water, supplied to it by means of countless, often black water-carrying tributaries. In terms of fish species, the Congo basin is – next to the Amazon Basin – by far the most diverse.  There are many tetras, upside-down catfishes, elephant-nose fishes, butterfly fishes, rope/reed fishes and cichlids. This habitat represents a cross-section from a small bay of the Malebo Pool.  Between the stones (the Congo River is full of them) and above the sandy bottom there is a fascinating selection of fishes to be discovered, but water plants are virtually absent.
Fish species: Zebra- and related tetras (Distichodus sexfasciatus, D. lusosso) Congo Tetra (Phenacogrammus interruptus) and Yellow-finned Congo Tetra (P. caudalis), Reed Fishes (Polypterus ornatipinnis, P. retropinnis, P. palma), Elephant-nose Fishes (Gnathonemus petersii), Butterflyfishes (Pantodon buchholzi), Upside-down Catfishes (Synodontis angelicus, S. eupterus, S. ornatipinnis, S. velifera, S. pleurops, S. greshoffi) and Jewel Cichlids (Hemichromis sp.).
Water plants: Water plants occur only rarely in this habitat.  Along the edges there may be some large Congo Water Fern (Bolbitis heudelotii), partially above water and partially submersed (when the water level rises), and possibly also the floating Hook Lilies (Crinum natans).  Sometimes, in little side bays, there are also floating water plants. 
Heiko Bleher's comment: Here we can see some fishes that inhabit and survive along the edges of the giant Congo River.  Some of these are in larger groups (for instance, the two Congo Tetras), which can only protect themselves this way  (in groups) against predators (such as Reed Fishes). The elephant-nose fishes protect themselves the same way, but they live closer to the bottom since they have to dig with their "trunk" in fine sand for food (micro-organisms). Butterfly fishes, however, live close to the surface for protection, because when an enemy approaches they simply jump out of the water. Upside-down catfishes are ‘at home everywhere’, and indeed they occur over nearly the entire tropical African Continent. They are omnivores, and with their long venomous spines (the venom is ejected only when the fish is attacked) they are virtually never afraid of any predator. The Distichodus-characoids, that can grow up to half a metre in length, feed primarily on vegetable matter, epiphytic growth and similar items.  They are too fast for most predators, as well as being too large. Cichlids are only visitors to this type of habitat. This goes to show that, when fishes are being kept under natural condition, such as shown here, and are well fed, they are a joy to watch and can also readily be kept together with predators in a community tank… just as in nature. In addition, if one watches carefully: the Distichodus sexfasciatus started right away to carry the correct size of small stones given in on part of the tank, to built its nest. And the very same, with slightly larger pebbles, was done by the Synodontis pleurops, which also is a stone-nest-builder (see photos).

The water values in Malebo Pool in this habitat were as follows:
pH 5.7 – 6.7, conductivity 22 – 55 µS/cm and the temperatures varied from 24.5 - 28.5°C.

The following companies have kindly contributed to setting up the habitat exhibit:
Tetra Werke GmbH: filter material and water conditioner
Kölle-Zoo: tank decorations - water-logged mangrove roots, fine-grained white sand (0.1 - 0.9 mm) and rocks (lava rock and red Jaspis [hornstone] and large boulders) are from Kölle-Zoo, Stuttgart.
Aquarium Dietzenbach:
Fishes:  The fishes on display in this exhibit have been imported and acclimated by Aquarium Dietzenbach, Germany.

Tropica:
Plants - Tropica, Denmark.
Project development and installation of exhibit: Aquapress - Heiko Bleher, Italy

This is typical Malebo Pool habitat, close to the river bank, where there are few plants in general; notice how quickly  the various fish groups have adapted to their respective niches, soon after their introduction. Just as in nature, Pantodon buchholzi along the surface (flying insect feeder), two tetra species, Phenacogrammus interruptus and P. caudalis (which feed primarily on plankton) in the open water; the lower regions are inhabited by larger tetra species of genus Distichodus, in this case D. sexfasciatus and D. lusosso, that often move through the tank individually (always in search of food … they are opportunistic feeders); the Gnathonemus petersii are bottom fishes, that usually search with their long trunks for food along the soft, very fine sandy bottom and among stones. They too have immediately adapted to their new home. Hidden (not seen in this photograph) are birchirs (Polypterus species), just as in nature.

This is an excellent action shot of elephant-nose fishes busily searching for food in fine sand, and the opportunistic squeakers or upside-down catfishes (Synodontis sp.) taking advantage of that.

This picture clearly shows how the tetra species immediately enjoy themselves and feel protected in the open water (left). Similarly, Distichodus sexfasciatus also profits from the food search by the elephant-nose fishes (right).

With their long trunk, elephant nose fishes can search the narrowest cracks (here part of a tree root)

for food. The pictures clearly show how the trunk is bring used to "feel" along the bottom,

to find out whether there is any food hidden there.

Upside-down cattfish (here Synodontis pleurops) as it picks up a stone that fits in to its mouth, in order to graze off any epiphytic material (left). Pantodon buchholzi in its habitat, close to the surface waiting for flying insects to come close to the water surface (right).

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