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Xiphophorus alvarezi Least Concern

Chiapas swordtail







15.00 cm

Males can reach 6" with the sword, but overall body length is typically around 3".


Semi-aggressive, Community

Males can be rough with females and territorial with other males, but otherwise leave other fish alone.


Herbivore, Omnivore

Tank Size

151.00 L

90.00 cm x 45.00 cm


21.0 C - 26.0 C


Anything over a pH of 7.5 with a higher level of hardness.



Other Information

Early developing males will develop "swords" on their tails and gonopodiums at around an inch in length. Later developing males, or females that turn into males will typically get (somewhat) close to their maximum body growth before developing male features. Both sexes will develop intense red horizontal stripes along their bodies. This is further accentuated in the gold and albino forms of the species available in the hobby. Given the nature of the fact that most available in aquaria are closer to wild populations in terms of ancestry/genetics, they will typically leave fry alone.

It is uncertain as to whether or not xiphophorus are sequential hermaphrodites or just have dominance based sexual maturity, however I personally think it is both, as I have seen females drop fry and later become males. Some males will develop early to spread their genetics before larger males (who inherently will have a better chance at attracting mates) mature and get the chance to pass on theirs. Females will additionally transition to become male in the event that there are too few males in the population, however this can backfire, as they have no way of communicating this to eachother before the process is started, and can sometimes result in all the females becoming male.


Spawning Method



Spawn Size

30 fry

Breeding Season or Trigger

Presence of dense vegetation to make the female feel secure enough to drop fry.

Fry Care

Fry can be left with parents and fed on dry foods, such as flakes. Fry should be removed from the parents' tank if sufficient hiding spaces are unavailable, or if there are proficient fry predators.