Montezuma Sword-Tails (Xiphophorus montezumae)

Montezuma Sword-tails (Xiphophorus montezumae)
Xiphophorus montezumae is a wild type sword-tail that gets an average of just over 2 inches in body length. They do occasionally reach 3 inches in body size. They usually have a black spotting or mottled color on a pale back color. As with many livebearing fish, males can be distinguished by their specialized anal fin. They also possess an elongation of the cadual fin (tail fin). This elongation is what gives Xiphophorus species the name "sword-tail". Females do not possess the sword-tail.

Captive Care
Montezuma sword-tails (often called "monties") are fairly easy to keep happy. They should be kept in groups with a ratio of one male to every 2 or more females. A 30 gallon long style aquarium can house a group of up to 6 adults. The aquarium should have some areas that densely planted (with live or fake plants) and some open areas. If you have enough cover, fry will survive with the adults.

Water Quality
As with all fish, stable, clean water is the most important to these pretty sword-tails. As long as the water is parameters are stable and the water is clean (no ammonia or nitrites, low nitrates, low dissolved solids) they should be able to adapt to most pH and hardness levels. Having said that, it is probably a good idea to keep their pH above 7.0 and below 8.0 and the dH between 10 and 20. They seem to handle temperatures between 68*f to 82*f fairly well. They may not breed at the lower and higher ranges, but that is just a guess. If kept in the higher range, remember to add extra aeration as warmer water does not hold oxygen as well as colder water. Also, never lower temperatures more the 2*f every few hours and do not raise them more 4*f every couple of hours. Stability and avoiding extremes is the most important thing.


Food
Monties are not picking about what they eat from what I have seen. As with most fish they do best on a variety. Use a couple of different flake foods (I suggest one brine shrimp flake, one spirulina flake and a generic tropical flake) and supplement with live foods (brine shrimp, clean blood worms, mosquito larvae, fruit flies, be imaginative!) and with frozen foods (brine shrimp, blood worms, mysis shrimp . . .). If you give them good nutrition and good water they should grow and breed for you.

Tank Mates
If you wish to keep monties with other fish, avoid mixing them with other sword-tails or platies or you may get some hybridization. They can safely be mixed with goodeids and I believe fish in the genus Poecilia. They can also be mixed with some peaceful tetras (stay away from nippers, the long swords are very tempting!), and peaceful bottom feeders such corydoras catfish. You can try a variety of tank mates, just remove any that aren't working out.

What Makes Monties So Special?
Perhaps the most stunning feature of montezuma swordtails is, well, their sword! Mature males will often have swords that are longer than their body. Even young males have long swords that usually equal the length of their body. Not only is their sword impressive, but they are not a drab fish. Even the females are nice to look at. Their dorsal fins are rather tall and they are not usually shy to display!

A Confusing Past
In the past a different fish was being masqueraded in the aquarium hobby as montezuma sword-tails. This fish was X. nezahualcoyotl. This other sword-tail has a shorter body and much shorter sword. In 1980 the true montezuma sword-tail was rediscovered in Mexico and the confusion was straightened out. Since the rediscovery monties have experienced a big rise in popularity, this popularity boom can be greatly attributed to the males extremely long sword. To read an excellent little two part series of articles on the history of the montezuma sword-tail and on the variation of color I highly recommend joining the ALA (American Livebearer Association) and ordering issue #196 and #197 of their bimonthly bulletin, Livebearers.


These guys are a gorgeous wild type swordtail. A friend of mine has a small colony of mottled monties and they are stunning! Someone was nice enough to send me some fry, so I now have some little babies swimming around my tank. They however are mostly looking to be males. I may have 2 females, but the others are boys for sure. Once they are bigger, I will probably trade extra males into the local store and order a few more females online.

Credit for the awesome montezuma sword-tail pictures goes to scott361