This is the king
of swordtails, yet it is rarely kept in any
real numbers, occasionally showing up at auctions. When it
does, it will often bring up to $100 a pair. Of the 4
populations of montezumae kept in the hobby, the Tomosopo
is the most colorful while also being one of the largest,
with possibly the longest sword. The montezumae behavior
is the most "wild" of any of the swordtails, making it a
truly exotic fish to keep. They can be shy, often hiding
in the plants, and react to sudden or unexpected movement.
However, as they become comfortable with their environment,
and their numbers increase, they will spend their time out
in front showing off at one another.
They should be kept in
an aquarium of 30 gallons or larger
with adequate filtration.
Moderate aeration with some water
movement and consistent
water changes will keep this
species comfortable. 10-30
young are born approx. monthly.
They generally do not eat
their fry, which should be
caught and raised separately. Occasional
live foods are
not required for their survival, but its inclusion in
their diet strongly supports consistent
These bottom pictures
show the incredibly long sword,
and it seems to grow throughout their life, often
reaching close to twice their body length in older
fish. Though not as heavy bodied or large as the
X. mayae or
X. helleri Rio Otapa,
these will still
reach 5.5 - 6 inches. See "How big can
Thank you Sumer Tiwari for the two bottom photos.