We traveled to the Rio Indio near the pueblo of San Martin yesterday hoping to collect.
This was the first Panamanian river I’ve encountered with so much algal growth, and yet not one fish.
Usually large schools of tetras are common even in the shallows.
After a number of casts, and not one tetra, we moved on toward the head waters of the Rio Indio, at the nearby mountains edge.
Within a half mile, the lack of tetras, and swaths of algae became clear, a very pungent pig farm appeared at at the rivers edge.
As we moved on beyond the degradation zone, toward the small streams that cascade down the Cerru Quintal mountain, and became the headwaters of the river, and fish life finally appeared, and algae became scarce.
Schools of Tetras and a few Andinoacara cichlids showed up.
I hadn’t bother to test the waters, down stream since we hadn’t collect anything, but with the now more abundant fish life, it seemed worth while. At this point, up river of the dead zone, the pH was around 8.2, and nitrates were undetectable.
Nitrate above, pH below
Since only a few Andinoacara were visible, and I already had plenty, we moved further south, toward the Rio Los Lotes, but only caught tetras, which were thrown back, but a few small, mixed gobies and were kept.
As we collected, typical of the rural area, horses are often lead thru the rivers.
