AMAZONAS
over fallen tree trunks,
tearing our pants and
scratching our legs. When
we finally arrived, though,
I was able to collect many
of these orange dwarfs
with my first net pull. A
small, knee-deep blackwa-
ter stream (80°F/26.7°C, 126 μS/cm, pH 7.25) flowed
through the middle of the marsh. Pseudomugil luminatus
lives here along with Melanotaenia ogilbyi and the Pore-
less Gudgeon dwarf goby Oxyeleotris nullipora. On the
way back, we got a bit lost in the swamp, but we finally
arrived, exhausted and filthy, back at the car.
A second location, also hidden deep in the rainfor-
est, was much easier to reach. Local loggers had already
cleared a road into the forest, and we followed it for
about a mile (1.5 km) before reaching a small blackwater
stream (82.7°F/28.2°C, 7 μS/cm, pH 4.85). Pseudomugil
luminatus were less numerous here and were yellowish,which is why Eko collected and exported them from
the first location rather than this one. Eko later told
me that the “Red Neon” form occurs exclusively in the
blackwater swamps in the Iwaka drainage, but the first
location he had taken us to was the only place where he
had found the bright orange specimens. At the second
location, Oxyeleotris nullipora was the second most com-
mon fish species. We also found Melanotaenia ogilbyi and
young Mogurnda cingulata. These pretty fishes are also
found in other marshes along the new road to Nabire. If
only I had known how close we had been to the habitat
of the “Red Neon” in 2011 and 2013!
I found P. ivantsoffi, but never P. luminatus, in the
Wataikwa drainage and all the other black waters and
marshes I examined. In 2011, in a marsh near the SungaiThe color of the males can vary within a population of Pseudomugil
ivantsoffi. This fish has a lot of red in the two dorsal fins, while the
specimen at the back has pure yellow fins.These Pseudomugil ivantsoffi
from a blackwater swamp in
the drainage of the Sungai
Wataikwa have a yellow base
color. After some time in the
aquarium, however, they take
on the normal gray base color.Everyone who took part
will remember the trek to
Pseudomugil luminatus’s
habitat for a long time!