Interzoo 2008 – Biotope 4

Authentic Biotope Aquarium

Paraguay River – Paraguay


Tetra presents Heiko Bleher’s authentic

Biotope from a small affluent to the Paraguay River in Paraguay, sponsored by Tetra.

Habitat: The Paraguay river is the 5th largest river in South America with its 2550 km in length. It flows from Brazil through the middle of Paraguay before it makes border with Argentina and joins the Paraná to merge into the large La Plata river delta. Here in Paraguay, south of the metropolis Asunción, merge several smaller creeks into it (there is an aquatic labyrinth of rivers, lakes and creeks) and the one shown here is such a typical one. And such a creek contains a large diversity of fishes and is rich in aquatic vegetation (normally only known to such an extent from the Brazilian state of Mato Grosso were the Paraguay has its source). Smaller characoid fishes and dwarf Corydoras (swimming in open waters, rarely over ground) next to sucking catfishes (such as Otocinclus, Cochilodon, Ancistrus) as well as cichlids of the genera Apistogramma and Gymnogeophagus, and bottom living characoids such as Parodon and Characidium species, and even freshwater stingrays enter such sandy habitat frequently. 

Fishes: Potamotrygon brachyura (1), Gymnogeophagus meridionalis (8), G. rhapdotus (6), Apistogramma sp. (10), Aphyocharax paraguayensis (30) and P. rathbuni (30), Mimagoniatus inequalis (15), Parodon affinis (6), Otocinclus sp. (20), Cochilodon sp. (5), Corydoras paleatus “high fin” (12) and Corydoras pygmaeus (25).

Plants: Eichhornia azurea, E. diversifolia, Eleocharis acicularis, Heteranthera zosterifolia, Lemna minor, Phyllanthus fluitans, Lilaeopsis brasiliensis, Ludwigia inclinata, Cabomba furcata and Myriophyllum aquaticum.

Heiko’s comments: The affluents of the Paraguay, north and south of the capital city, are rich on fish species, many enter from the main river into these habitats full of aquatic vegetation, as there is plenty of food, shade and protected areas for several species to survive. Freshwater stingrays enter frequently such habitats, to bring birth to their young, but also to feed on toads (tatpoles), crustacea and smaller fishes. The smaller characoids live here in groups, as well as the free swimming Corydoras pygmaeus (I encountered millions in migration in such smaller creeks, quite often), but there are also bottom dwelling fishes like Corydoras and Parodon living over sandy grounds. The Apistogramma species live only in the very shallow water zone, along the edges. The larger cichlids, mainly of the genus Gymnogeophagus, (and note the two species shown, G. rhabdotus and G. meridionalis, look extreme similar, and to my knowledge cross in nature are common) live in the deeper regions. Many of such habitats are still undisturbed and therefore the aquatic flora and fauna is still very rich. Given the right habitat and a little temperature rise like here, they start immediately to spawn. On the first day of introduction… (see photos).

The chemical water parameters in this biotope were pH 5.9-6.5, the conductivity between 28-34µS/cm and temperatures from 26.7 – 28.3°C (in their winter the water temperature can drop down to 19°C and even lower).

The following companies have contributed with materials and live stock:

Tetra: Filter and filter material, foods and water chemistry.

Kölle-Zoo – Stuttgart: Décor elements: different stones and white sand 01-09mm as well as Aquaria gravel 2-4mm and driftwood.

Aquarium Dietzenbach and others: Fishes – the fishes have been collected in part by Heiko Bleher, some bred by Peter Günnel and others imported and quarantined by Aquarium Dietzenbach, Germany.

Tropica: Plants have been supplied by Tropica, Denmark

Idea and authentic biotope decoration: Heiko Bleher, Italy



4. Aquarium – 600 litre –

Heiko Bleher’s aquarium display of Paraguay River Biotope below water







Every species in the authentic Paraguay small stream habitat finds immediately its niche and starts to mate like the Gymnogeophagus below…


…or they filter the sand, as in nature…


…or clean the stone were the female will to lay its eggs…


…or fight the intruder


Corydoras paleatus need the fine sand and if given like here they feel great as one can see it right away after the decoration is done according to its nature


Also the Aphyocharax paraguayensis shows its brightest colour in the correct given environment…


…and the freshwater stingray Potamotrygon brachyura from this habitat searches – as in nature – for micro organisms in the sand, and also for tadpoles along the edges of the creek


And the different characoids dwell below the floating vegetation, as in nature

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