of a male and a female of X.nezahualcoyotl
The area in which X.
nezahualcoyotl is found is the Rio Tamasi drainage in the Mexican state of
San Luis Potosi. In its natural state the fish is found mostly in
fast-flowing waters and would probably appreciate power filtration in the
This is the kind of fish
that is rarely or never found offered for sale in a pet shop. The only way
one is likely to obtain them is by belonging to a club or attending one of
the club auctions that take place in various areas during the year. Sally
and I got our original pair at an auction in Kitchener. The sellers were
Brian and Susan Glazier and they later generously gave us the remaining
three or four females from their stock.
The characteristic that I find
most appealing about these fish is their size. They are decidedly a dwarf
swordtail when compared to X. helleri which can grow to more than 15 cm TL.
X. nezahualcoyotl females will grow to 6cm TL while males make only 5.
This smaller size makes it quite possible to keep a pair or two very
comfortably in a five or ten gallon tank and still be assured that with
proper food and care they will attain full size.
My original pair were given
a ten gallon tank to themselves and a large clump of Java Moss was added
in anticipation of fry. The female did regularly (about once a month)
produce babies but, whether she only threw a few or whether they ate some
of them, there were only two or three each time. And then of course the
By this time, a few of the fry
had grown to about an inch in length. One of them looked "different"
and very shortly after 'daddy's' death, he started to grow a swordtail and
took his place. The sequence of events may have just been coincidence but
on the other hand the male characteristics definitely developed
immediately upon the demise of the adult male.
This fellow grew into a
nice looking adult and was obviously functional since several females have
now produced batches of fry. On top of this the number of fry has
increased to a dozen or so per batch. Strangely enough though, he appears
to be the only male in the tank although several of the inhabitants are
the size at which he began to develop male traits.
At the time of writing this
article, the original female, one of her older daughters and the male have
been moved to another tank. I hope that they will continue to reproduce
here and that at least one of the fish in the original tank will turn out
to be a male.
If no more males turn up it
may be necessary to play games with pH or temperature to see if the sex
ratio can be made more equal. I would rather it were just a matter of
removing males as they develop!
Note (D.Montanari) Next
spring I’ll probably receive some specimens of X.nezahualcoytl “Ocampo”.
I will let you know my experience with them