Stingray Information

    In the last few years Freshwater rays have become increasingly available and popular and tanks have become larger and cheaper, making them a reasonable pet for the dedicated home aquarist.


    Although some other major rivers around the world have ray populations, most freshwater ray species are found in Amazonia, and as with its other flora and fauna, the Amazon system has an abundance of ray variants found all along the river and in many of its tributaries, from Peru and Colombia in the West to the mouth of the Amazon in North Eastern Brazil. Some ray species are also found in other tropical South American rivers with no direct connection to the Amazon.


    Stingrays are very ancient species, tracing their evolutionary history as far back as 300 million years. The most commonly found species in South American rivers are Potamotrygon. There are also rays known as China or Coly rays , about which little is known at this time. It is thought that all of these Amazon rays are most closely related to Pacific Marine rays. Their isolation would have occurred when the Andes Mountains rapidly rose up about 15 million years ago, blocking the Westward flow of the river as it then was and forcing it to flow east all the way to the Atlantic, trapping many rays in the new system.


    This isolation and the Amazon’s Tropical climate and seasonal massive changes in water levels created ideal circumstances and great pressure for evolutionary changes, as represented by the huge variety of stingrays found in just the one system. Even individual species that are found along the whole river, such as Motoros and Hystrix, are polymorphic, each exhibiting their own wide range of colors and patterns as habitat and available diet change subtly between regions.

Article on Husbandry, Biology, and Reproduction of Potamotrygon.

by Ronald G. Oldfield
University of Michigan,

Department of Ecology and Evolutionary Biology

Husbandry of Freshwater Stingrays of the Family Potamotrygonidae

by Dr. Richard Ross

Institute for Herpetological Research

 

 

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