Xiphophorus nezahualcoyotl

 Synonyms: Xiphophorus montezumae, X. montezumae Hamburg 64

Common Name: Neza swordtail

Family: Poeciliidae

Sub Family: Poeciliinae

Distribution: There are two separated populations. One is located in Rio el Salto in San Luis Potosi, Mexico and the other is in Rio Santa Anita.

First Introduced: 1964

Size: females 6 cm, males slightly smaller.

Sexing: Males have a gonopodium.  They also have a long sword, yellow-orange in colour outlined in black.  They have a few zigzag horizontal stripes.  Dominant males also get approximately 8 vertical bars on their sides.  The dorsal is yellow with black spots (subdominant males also seem to have what appears to be a gravid spot).  Females have the colouring of the subdominant males.  They also show a gravid spot.  My largest female also showed signs of the vertical barring of the dominant male.
There seems to be two varieties of this fish.  One also has a dark spot on the caudal peduncle

Breeding: Is a livebearing fish.  The female can produce 15-35 fry every 4 weeks or so.

Requirements: Alkaline (pH 7.5 and  higher) water is recommended.  A temperature of  24-28°C is best for this fish.  They however do alot better on the lower end of this temperature range.  Do not mix this fish with any other Xiphophorus species as interbreeding will occur.

Feeding: I fed my fish basic flake, spirulina flake and brine shrimp flake.

I had obtained these fish from a fellow hobbyist. I had gotten more males then females.  They were immediately  placed into a 20 gallon tank.  This tank was barebottomed.  There were also a few Australian rainbow fry growing up in this tank.  There were a lot of plants in this tank, all floating (mainly hornwort).  Filtration was provided by a sponge filter.  The temperature in the tank is approximately 78°F.  A few weeks later I noticed a few fry swimming in the plants carefully hiding from the rainbows and the adults.  As I did not have a spare tank at the time I left them in there.  I did put in a bit more hornwort to help them hide.   I would notice a few new fry occasionally in this tank and that they seemed to survive.  I did notice a problem with the subdominant males in the tank.  They seemed to get chased a lot and then would become very skinny and end up dying on me.  The first batch of fry starting to show a gonopodium one by one.  I got all males from that first small batch.  I did however gt another female from the second batch and I believe she has just now started breeding as the males are very interested in her.  I seem to get more fry surviving now then I did earlier leading me to think that it may have been the rainbows that were more of a problem than the parents.  I did remove the rainbows from the tank when they got big enough to go in a different tank.  I never fed the fry anything special.  They would go for the crushed up flake and seemed to take that extremely well.  I find the males of this species to be very attractive if somewhat understated in their looks.

© Copyright 1999-2003 Lisa Brinkman
All Rights Reserved

Suggested Reading:

Baensch Aquarium Atlas Vol. 2 by Dr. Rüdiger Riehl & Hans A. Baensch

Livebearing Fishes - A Guide to their Aquarium Care, Biology and Classification by John Dawes

Livebearing Aquarium Fishes by Manfred Brembach

Atlas of Livebearers of the World by Lothar Wischnath

Exotic Aquarium Fishes  by Dr. William T. Innes

Guppies, Mollies, Platys by Harro Hieronimus

To see other references on livebearers:

Livebearer Book List

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