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un po' di info dal sito di H. Bleher:
Rio Xingú, Amazon, Brazil
Habitat: Rio Xingú is a tributary in to the lower Rio Amazonas from the right. With a length of
more than 2,100 km, it is the 8th longest arm of the Amazon River. It is a clear water river, which
the Brazilians refer to as água clara. I am showing here a habitat from the open water below Vitória
do Xingú, the transfer location of merchandise to the upper Xingú (because south of here start the
gigantic river rapids). In this area, the river bottom consists of fine white sand and many small and
medium-size, round stones. The river banks are in part still densely covered by primary forest. This
is the area where there is a very diverse freshwater stingray fauna (the only other river with more
freshwater stingray species is the Rio Verde). There are virtually no water plants.
Fish species: Two unidentified freshwater stingrays (Potamotrygon sp.) und 10 small Peacock
Stingrays (Potamotrygon motoro), Red Hook Metynnis (Myleus rubripinnis) and Black-barred
Metynnis (M. schomburgkii), as well as 3 newly discovered Metynnis (Myleus sp.), Piranhas
(Serrasalmus altus), Eye-spot Cichlids (Heros cf. severus), large Suckermouth Catfish
(Pterygoblichthys sp. and Hypostomus sp.) as well as Golden Whip-tail Catfishes (Sturiosoma
aureum).
Water plants: There are no water plants in this habitat. In quiet bays there are sometimes Water
Lillies (Nymphaea species), Bladderwort (Utricularia species) and floating plants, such as Pistia
stratiotes and Salvinia natans. Along the river bank there are occasionally large Sword Plants, such
as Echinodorus grandifolius.
Heiko Bleher’s comment: I was able to show that there are by now 7 different stingray species in
Rio Xingú, but I am certain that there are still more, most of them no doubt still unidentified. There
are no water plants (as mentioned before, only during the high water period one finds floating plants
and grass). Large groups of Disk Tetras or silver dollars (genus Myleus, as shown here, but also
Metynnis species) are also often crossing the path of stingrays. Occasionally, there are also large
Armoured Catfishes and Eartheaters (the latter are not shown here). These occur mostly over sandy,
often over rocky bottom substrate in Rio Xingú. In contrast to the often wide-spread opinion that
stingrays require giant aquariums, I must – based on my own extensive experience – disagree. Of
course, these magnificent fishes must be given sufficient space (and fine sand as bottom substrate).
The sand is absolutely essential for the food search by freshwater stingrays. These nocturnal rays
tend to bury themselves in the sand during the day (with often only the eyes protruding above the
sand) in order to rid themselves of parasites and to seek protection from Piranhas that often stray
through their territory during the day.
In the Xingú habitat the recorded water values were: pH 6.25 to 6.55, conductivity 21 - 22 μS/cm,
day temperatures: air 36.5 °C., water surface 28.5 °C. and at a depth of 2 m 27.9 °C. (where most of
the fishes shown here live).
Rio Xingu and Tapajós, Brazil
Habitat: The Xingu and Tapajós are two major right-hand-afluents of the Amazon River in Brazil.
In particulary the former is known for its wilderness and still many Indian tribes live along its shore.
The biotope shown is precisely that of the Loricariids in both rivers. Loricariids – also known as Lcatfishes
– hide mainly in parts of the Xingu between such layers of rocks, they live and reproduce
there. Never is not any aquatic plant near, except for from algae over grown rocks. Other fishes
which may be found near are mainly charachoids of the familiy Anostomidae and from the family
Cichlidae the genera Crenicichla, Teleocicha and Retroculus mainly.
Fish species: Peckoltia cf. vittata, Peckoltia species, Pseudoacanthicus species (one named
“Titanic“ from the Tapajós), Hypancistrus species, Hypancystrus zebra, Hypostomus species and
many species more. A total of almost 250 speciemens are in the above aquarium – look closely and
you will see several of them!
Heiko Bleher‘s comment: I have found Loricariids exactly in such biotops mainly in the Xingu
south of Altamira – also already in 1975 the later described Hypancistrus zebra – and many
different species as shown here up the Rio Xingu, crossing more than 30 very dangerous caterats.
These fishes live exclusively in such biotops and the same should be created for home aquaria!
Ultima modifica di Raf28; 26-12-2012 alle ore 13:57.
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