Xenotoca eiseni

Xenotoca eiseni is a Poisson of the family of Goodeidés.

This fish was described for the first time by Rutter in 1896. He had baptized it “ Characodon eiseni ” in the honor of the geologist named Gustave Eisen.

Description

Xenotoca eiseni is robust and massive. Its angular contours give him a particular form, almost rectangular. Its head pointed and is finished by a all small mouth. The dorsal fins and anal of this fish are located far from the head. All these characteristics give him a rather strange silhouette with the first glance.

As at the majority of fish, the male Xenotoca eiseni is coloured much more than the female. It presents a caudal Nageoire orange and the posterior part of its body is blue steel. Sometimes, it will have the sides gilded yellow. In addition to being coloured, the male is different from the female by its andropode which is in fact a modified anal fin which is used for the reproduction.

The female is larger (7-8 cm) that the male (5-6 cm) and squater. It has a very large belly right before the Accouchement. It does not have the colors of the male, it is entirely yellow beige.

Xenotoca eiseni is a species of Goodéidés which one finds with the Mexico, in the rivers Rio San Leonel, Rio Tamazula and Rio Grande of Santiago. These rivers are located on the south-western coast of the Mexican central plate. He lives as much the limpid rivers with strong water flow as the stagnant ditches at the edge of the road.

In Aquariophilie

This fish is thus rather tolerant vis-a-vis the conditions of water. On the other hand, the optimal parameters to make it happy are a fairly hard water, between 15 and 20 dGH, a pH ranging between 6 and 8 and one temperature varying between 15 and 32°C. To arrive at these conditions, one can quite simply use the tap water to which one adds approximately 1 spoon to salt table of Epsom by Gallon (the salt of Epsom is used to harden water and helps to keep beautiful plants in health).

Xenotoca eiseni is not either capricious when comes time to eat. He eats of all and good heart. This omnivore nourishes Algue S, flakes, of food alive and frozen, in fact, it will accept almost all that one gives him. It is recommended to nourish them well before and during the reproduction to have layings which are abundant and in good health.

Xenotoca eiseni is a relatively peaceful fish. It sometimes happens to him all the same to eat the fins of the other fish which divide its aquarium: it can be thus advised to make it cohabit with robust species, with small fins. It may be that it decides to eat the plants of the aquarium. Xenotoca eiseni will be at ease in a vat planted well of robust plants, with hiding-places, at least 15 gallons. Certain authors affirm that a too small vat would make fish more aggressive. As he is a good eater, it is important to have a good system of filtration and to change water regularly.

Xenotoca eiseni is very good Goodéidé to initiate itself with the breeding of this family of ovoviviparous. It is easy to keep, not very capricious and its alevins are robust and easy to nourish.

Reproduction

Before the Coupling, the male deploys its fins in front of the female which starts to tremble as a positive response.

Xenotoca eiseni is a species Ovovivipare S. the male has a sexual organ called andropode which is used for the internal fertilization. The andropode is the equivalent of the gonopode at the Poeciliidae. The anal fin of Goodéidés is separate into two. The Alevin S develop in the cavity ovarienne female. It must be fertilized with each range, contrary to the other ovoviviparous species (as the Guppy S) which can have more than one range by fecundation.

Xenotoca eiseni is a fish matrotrophic. This means that its Embryon S nourishes nutritive elements coming directly from the mother. In fish matrotrophic, all the mother-embryos exchanges pass by the embryotrophe. The embryotrophe is a liquid very viscous container full with nutritive elements which filled the cavity ovarienne in the female.

During the Gestation, which lasts approximately 60 days, the embryos bathe in the embryotrophe. They draw there the nutritive elements for which they have needs to develop and they reject metabolic waste there. The trophotaeniae are prolongations of the intestine which are at the base of the Anus alevins. They are used for the exchanges between the mother and her embryos during gestation. One can compare these trophotaeniae with the umbilical cord Mammifère S. Two or three days after the birth, these structures disappear.

During the childbirth, the small ones are born the tail in first, the belly upwards. They are already robust and will eat flakes émiettés little time after their birth. Their small tail presents already a yellow, male and female coloring included/understood. Certain references indicate that a laying can contain up to 60 small. The parents very seldom eat their small. A little foam of Java in a corner of the aquarium will make it possible to the young people to hide during the first hours of their life.

The males can be differentiated starting from age the 2 months. They do not have their beautiful coloring but their anal fin changes in andropode. By looking them of near, it is possible of the sexer.

The life expectancy of this Goodéidé is of approximately 5 years. It seems that he reaches his sexual maturity towards the 2 years age.

References

Aquarium Atlas, Volume 2, Mergus
Livebearing fishes, Scott, P.W., Tetra Close
Guppies, Weakened and Platys, Hieronimun, H., Barron' S Edition
Maternal-embryonic relations in viviparous teleosts, Schindler, J.F., 1993, The Newspaper off Experimental Zoology, 266:378 - 393
Xenotoca eiseni, Ravard, J. - L., April 2003, Friends of the 1932-Strasbourg Aquarium, http://www.aquarium32.com
Xenotoca eiseni, Fischer, R., November-December 1992, Minnesota Society Aquarium, http://www.mn-aquarium.org/masart76.htm
Site on viviparous in general the

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