01-16-2012, 01:17 PM
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Originally Posted by nicolaas
Thanks,but they don't talk about Metynnis hypsauchen
That's because it is not feasible (at least for me
) to give a definitive answer. But I can perhaps make some suggestions.
Some fish species occur only in one specific watercourse, for example the coral red pencilfish Nannostomus mortenthaleri is known to be endemic to the Rio Nanay in Peru. Ascertaining the water parameters of this river will thus tell us the preferred habitat for this species. But Metynnis hypsauchen, as I noted in the profile, has a much wider distribution. For example, it occurs in the Guyana's, the upper Amazon basin and the Rio Paraguay south of the Amazon basin. The Amazon basin alone occupies an area as large as the continental United States minus Texas, so we are dealing with a vast area and every type of water.
Several of the rivers draining the Guiana Shield are relatively muddy, what some refer to as whitewater; I won't go into the difficulties of using this name, but it implies rivers that are somewhat "café au lait" in colour, a creamy brown like coffee with milk in it. The Rio Paraguay is basically a clear water river, though it has at least one blackwater tributary, the Rio Negro--not to be confused with the enormous Rio Negro that is a northern tributary of the Amazon itself. So now the problem is finding out which specific stretch of these rivers may be inhabited by Metynnis hypsauchen, and this I do not know. From this information, one may assume the fish occurs in clearwater, perhaps blackwater and perhaps whitewater.