Xiphophorus nezahualcoyotl (Rauchenberger, Kallman & Morizot 1990)
Etymology:
Xiphophorus: Greek, xiphos = sword + Greek, pherein = to carry
Nezahualcoyotl: Named after the poet-philosopher emperor of Tezcoco (Texcoco), considered to be coequal with Montezuma, monarch of the Aztecs in the Aztec Triple Alliance
First description:
Rauchenberger, Kallman & Morizot 1990
Rauchenberger, M., K. D. Kallman, AND D. C. Morizot (1990) Monophyly and geography of the Rio Panuco basin swordtails (genus Xiphophorus) with descriptions of four new species. American Museum Novitates 2975, 1–41.
Common Name:
Northern Mountain Swordtail
Affectionately known as Nezzie
Synonyms:
Xiphophorus montezumae montezumae: Rosen, 1960:
Xiphophorus montezumae ((Hamburg, 1964)): Lechner and Radda, 1987:
Xiphophorus, sp. nov.: Zimmerer and Kallman, 1988:
History:
Collected by K. D. Kallman, D. C. Morizot, and M. Ryan on 6th April 1985.
X. nezahualcoyotl has previously been confused as X. montezumae, some if not all previous reports in the past to experimental work with X. montezumae actually refer to X. nezahualcoyotl.
Group:
Xiphophorus nezahualcoyotl is one of nine northern swordtails and belongs to the Montezumae clade consisting of consisting of X. montezumae, X. nezahualcoyotl, X. continens
Type Locality:
Arroyo Gallitos, 0.5 km west of Gallitos, an internal drainage, Tamaulipas state, Mexico.
Distribution:
Rio Tamesi drainage, San Luis Potosi/Tamaulipas states, Mexico
Populations:
El Salto, Mexico
Puente el Nacimiento
Rio Tamesi Ocampo
Habitat:
Generally found in streams with strong currents over substrates of sand, gravel or rocks (Very rarely over mud or clay) with usually sparse or no vegetation.
Size:
Male 5cm female 6cm
Distinguishing characteristics:
A deep bodied medium sized species of swordtail.
Colour/Pattern Variability:
Males
A base colour of pale brown, overlaid with a sky blue the lateral line is formed of multiple zigzag lateral lines. Black spots can appear on the body, these can form random patterns which are not identical to both sides.
The dorsal fin base is long and when the dorsal fin is lowered it extends further back along the caudal peduncle
The caudal peduncle is relatively deep with many populations showing a caudal blotch. The sword is yellow with black edging and distinctly upturned (although fairly straight in larger males), sword length is on average just over half the length of the body.
Females
A base colour of pale brown, overlaid with a sky blue the lateral line is formed of multiple zigzag lateral lines. Black spots can appear on the body, these can form random patterns which are not identical to both sides.
Husbandry:
Can be kept in a biotope aquarium with a gravel and rock base using a power filter to provide the current or a planted community aquarium for similar sized fish
X. nezahaulcoyotl is found at lower elevations than X. montezumae and therefore requires a slightly higher temperature, Derek Lambert recommended 25 degrees
Breeding:
If well fed and maintained in an aquarium with plenty of hiding places, this species can be flock-bred, however it is recommended to remove the female to a heavily planted spawning tank about a week before birth.
Broods are produced on a monthly cycle with fry numbers of 25 on average.
Remarks:
A sister species to Xiphophorus montezumae, Identifiable by having a smaller adult size with a deeper body, a shorter sword that is distinctly upturned.
References:
Rauchenberger, Kallman & Morizot: Monophyly and Geography of the Rio Panuco Basin Swordtails (Genus Xiphophorus) with Descriptions of Four New Species
Derek and Pat Lambert: Platies and swordtails
