also heavily spangled. Maximum size is
around 4 or 5 inches.
Captive G. meridionalis can be quite
territorial during the breeding season.
However, they will coexist peacefully if
provided refuge in the form of submersed
wood and stones to define territories. They
are also harmless to plants that are securely
fixed in the aquarium.
In nature, they can be found in clear
water over a sandy or rocky bottom. They
spawn in the summer months and take
vigilant care of the young. Typical of most
substrate spawners, both parents guard
the fry—with the most ferocious guardian
being the female.
SP. AFF. MERIDIONALIS
This cichlid has been widely and
erroneously kept and sold internationally
as G. meridionalis. G. sp. aff. meridionalis is
one of the most widespread gymnos in the
country, as it inhabits the south, west, and
central areas of the country, throughout
the Río Uruguay Basin, the Río de la Plata
Basin, and small coastal drainages to the
The fiery blue, scarlet, and yellow
coloration of wild-caught adults can be
breathtaking. Intense red coloration adorns
their dorsal, caudal, and anal fins. At the
top of the dorsal fin is a dark band that
characterizes this species. Blue spangles that
are either round or elongated are always
present in the caudal and dorsal fins.
These can make a fantastic aquarium
subject due to their primary colors and
small adult size. However, this fish is very
territorial and can become aggressive. Keep
them in aquaria either alone or with larger
fish that can take care of themselves. It
will accept most foods offered, greedily
consuming anything from dry pellets and
flakes to live food.
This highly colored species is a great
choice for the beginning eartheater keeper,
as it is easy to breed in captivity. When
conditions are to their liking (pH near
neutral and water temperature in a range of
73° to 77°F), spawnings are almost sure to
occur. They lay and guard about 300 eggs
on a site that has been previously cleaned.
In the wild, they are found among a
variety of habitats. We have collected them
via seine or castnet from muddy, sandy, and
rocky substrates, in moving water (small
streams to large rivers) and from small
lagoons. In the clear, still waters, we have
Gymnogeophagus sp. “Las Tunas.”
enjoyed observing these little animated fish
squabbling and protecting their broods.
Gymnogeophagus rhabdotus “Paso de la Lana”; G. rhabdotus is a relatively easy-to-breed
spawning gymno, G. rhabdotus has a limited
distribution from the Merín Lake and Río
Negro basins in Uruguay. They can show
great amounts of phenotypic variation,
and individuals from the Río Negro Basin
differ in color pattern from the common
Merín Basin specimens. Even within the
Merín Lake Basin, there exists much
variation in coloration. A perfect example
is the headwater-dwelling G. rhabdotus race
called “blue neon.” These have a much
more intense blue-to-violet coloration in
their body and fins. Thankfully, all races
shimmer in glorious blue, green, or purple
when taken from the wild.
The main difference between this, G.
meridionalis, and G. sp. aff. meridionalis is
that G. rhabdotus exhibits a striped pattern
in its dorsal and caudal fins (as opposed to
dots). In morphology, it closely resembles
G. sp. aff. meridionalis.
This is also a great species to keep in
the aquarium, as they will take almost any
kind of food, have a wide tolerance range
in terms of water chemistry, and are easily
bred in captivity. However, they are not
a very sociable species and need to have
hiding places. A fine-sand bottom with
rocks and roots would be the preferred
setting. Under these conditions, they will
be compatible with durable plants.
In the wild, they can be observed in
clean, flowing waters with a muddy, sandy,
or rocky bottom. Sadly, most of their
natural habitats in the Merín Basin are now
starting to be degraded by the impact of