Río Santa Engracia
The Río Santa Engracia population is
notably different from both of the above
races. Its flanks are drably colored,
reminiscent of the gray to olive-brown body
of X. couchianus, with some males showing
a slight striping. But it makes up for this by
sporting a very large, yellow-bordered black
spot on its caudal peduncle. This population
has been known in the hobby since 1979,
and my late friend Derek Lambert had found
this race particularly robust and larger than
those from the Río Purificación. He felt this
was due to the latter species enduring years
of hobby inbreeding.
The Xiphophorus Genetic Stock Center
houses other strains or races of X. xiphidium.
These go by the names “San Carlos,”
“peduncular spot,” and “Aramberri” (no
longer in residence). My experience has
been with the Río Purificación population
and my observations will reflect this race.
These observations are in contrast to older
European accounts, which often claim the
species to be a difficult charge.
With males reaching about 1½ inches,
and females 2 inches, a small colony of X.
xiphidium can be housed minimally in a
standard 10-gallon aquarium that is well
planted. I have found that the species really
prefers cooler temperatures, from 60° to
75°F (around 72°F seems about right).
Higher temperatures over extended periods
(i.e., 24 hours) have proven fatal. Like most
inland livebearers, the species enjoys a pH
from 7. 2 to 8.0 with slight to moderate
hardness from 10 to 20 degrees.
The morphology of this fish includes
qualities from all three xiph types. The
body shape is X. maculatus-like, being
short and stubby, but its dorsal is somewhat
wider, with contrasting color, like an X.
variatus platy. But then males also sport a
rudimentary swordtail (really just a pointed
prolongation of the caudal fin). The tiny
sword is either colorless or slightly edged
Like many of the wild-type platies and
variatus, there is a slight hump-back build
(this has been notably bred out of retail
platies) in the species. It appears more
closely related to X. variatus than other
xiphs from an ichthyological point of view.
X. variatus is also the species in closest
geographic proximity in nature. Indeed,
older literature often references it as “X.
The sword platy Xiphophorus xiphidium, a dominant, blue, four-banded male in the Río San
will flock-breed and form a colony, provided
that they get enough plant cover and food.
This soon results in a xiphidium town that
proves very interesting. I have found Río
Purificación males “sparring” at an early
age. The older alpha males will often
intervene, as if to break it up. In reality,
the alphas are probably just asserting their
dominance over the colony and keeping
the other males in line.
Xiphophorus xiphidium, the platy with a
sword, is a livebearer that really should be
more popular and widespread. It requires
little space, and its colors and behavior
can’t be beat. What more can you ask for in
an aquarium livebearer?
Xiphophorus xiphidium appears to relish
algae in the aquarium (and in my outdoor
fish tubs), so include vegetable matter,
along with portions of a balanced flake
and small, safe, and live or frozen foods
like baby brine shrimp and daphnia. They
also relish newly hatched mosquito larvae.
A good diet combined with a planted
aquarium built on dark gravel will really
bring out a male’s fabulous colors (along
with a few choice females and some rivals
for their affection!).
Brood sizes are not large for such a small
fish, maybe about 20 on average (although
more have been recorded), but X. xiphidium