Biotope ID, not species...

[Siggi]

Hi, all.
I'm curious about the identification of biotopes, not an individual.
Take, as an example, the River Ucayali ... It's a white water river - am I wrong in my assumption that most of the populations (A. panduro, A. bitaeniata A. Agasizi) identified from that region usually do best in clear-water or even black-water conditions, i.e. low conductivity, acid and low suspended minerals?
Are the side streams and even smaller bodies of water of the main rivers not white water? Are the headlands filled with clearwater 'quebradas' in the rain season and after the showers in the remaining year and only the main rivers flow with white water?
Or do the fish from these rivers/rivulets thrive in "soft acidic water" that is what we 'fabricate' for the fish, but this is closer to white-water parameters and we lack the perception of how extreme the conditions are in "true" black-water...
The small tributaries to the typical white-water rivers - are they also white? or are they clear-water?

Answers appreciated - thx in advance.

 

[Mike Wise]

The Rio Ucayali (main channel) is a whitewater river, whose headwaters in the Andes Mountains transport a lot of silts and clays. The lower Rio Ucayali receives water from the rainforest, where the water is clear- to blackwater. It's the lower tributaries of the Ucayali where we find our apistos. Where I collected apistos in the Ucayali system (not the main channel) water values in apisto collecting sites were generally around pH 5.5 - 6, 35 µS/cm @ 25°C (77°F). I never tested the main channel, but TomC tested water near the mouth of the Rio Itaya on the Ucayali, where he collected Apistogrammoides pucallpaensis (a.k.a. A. sp. Ruth). Maybe he can supply better information on whitewater values. One whitewater stream he told me had a pH of 6.3 and similar conductivity to other clear/blackwater streams in the area.

 

[Siggi]

Thanks for your input, Mike.