This genus exists of swordtails and platies. The name "Xiphophorus " is a composition of two greek words, meaning "dagger" and "bearer". Looking at swordtails, you'd expect it to be referred to the swordshaped tail but it actually refers to the gonopodium.
Note: Not all swordtail males do develop a sword and with some platy strains males can develop a very short swordtail.
Swordtails inhabit waters ranging from Belize, Honduras, Guatemala and mainly Mexico. Platies however occur mainly in Mexico. Swordtails do occur in freshwater but also in brackish waters. They can even get used to marine water just like mollies. But just like guppies, swordtails were also introduced by man to other waters all over the world. For a lot of swordtail strains do occur in higher situated areas where it can be a lot colder which makes them excellent inhabitants in other colder areas. This tells us as well that we should label swordtails as being subtropical instead of tropical.
There are so many different swordtail and platy strains in the wild. The fancy swordtail strains we know are all derived from the Xiphophorus helleri and the fancy platy strains from the Xiphophorus maculatus and the Xiphophorus variatus. But again, besides these three... there are way more wild strains of swordtails and platies.

Note: Males of the xiphophorus species may develop a socalled "pseudo gravid spot". This phenomenon happens mostly with platy species in comparison to swordtail species. Mostly such a pseudo gravid spot will be developed during or after the transition of the anal fin into a gonopodium. It hardly happens before the anal fin's transition.This has got nothing to do with a female turning into a male. For that's a different story.

Above: An adult male Xiphophorus evelynae.
Note: Once a pseudo gravid spot has shown on a male's body, it will never dissappear.

Xiphophorus species are born with both male and female gonads. Generally spoken, an initial male will absorb the female gonads and an initial female will absorb the male gonads while growing up. But in some way this absorption doesn't always seem to happen the way it suppose to be. Which makes it possible that female specimens can change gender. Even when she's been pregnant before. But in that case, the female will keep her gravid spot. And the transformed specimens will be functional males when it comes to reproduction. But yes, also old females can change gender after they've had their defininite last batch of fry. In general, such a transition will take place after a a certain trigger. An example could be an unbalanced male/female ratio within the group or even a lack of hiearchy within the group. But there are more triggers to establish a sex change.
Males however can not change gender for the transition of the anal fin into a gonopodium is irreversible.

If there's a lack of males or even no males within a group but there are fry present, you'll notice that there will be fast developing young males. These males stay small in comparison to an average male's body size. This is to ensure the reproduction and the exsistance of the species.

Xiphophorus pygmaeus

One of the wildforms is the dwarf swordtail (xiphophorus pygmaeus). These dwarfs are to be found in the Pánuco River system in Northeastern Mexico.
It's a swordtail which really shows its wild nature in comparison to other swordtails. These are in some way shy fish which will hide when they can.
 Golden male
 Golden male
 Blue female
 Blue female 
There are two versions: the golden and the blue version. The blue version is not blue but that's how the wild colour is called. But note that both females of the blue and gold version are blue. So, a golden coloured female doesn't exsist.
In captivity they grow  up to 4cm.

Above: Xiphophorus pygmaeus combined with chocolate mollies and yellow top swords.

Above: Fry of the xiphophorus pygmaeus.

Xiphophorus continens

Another dwarf swordtail is the Xiphophorus continens and also known as El Quince swordfish.
This dwarf is to be found in Rio Panuco drainage in San Luis Potosi in mexico where it inhabits an enviroment with fast flowing water.

Just like the Xiphophorus pygmaeus, the males of this species carries also a very short sword. And some males just won't grow a sword which is also comparable with the Xiphophorus pygmaeus. The same goes for their size.
The stripe on both sides seems clearly different from their dwarf relative. 
It's a friendly swordtail which is suitable for smaller tanks but be sure of it that they still have sufficient swimming space for they are very vividly. 
Gestation will take up 3,5-4 weeks in general and the amount of fry won't be that large. A good batch will be at 10-15 fry each drop.

Above and below: A pregnant adult female.

Below: An adult male.

The males are quite slender in body build in comparison to females.

Xiphophorus multilineatus

Also a very interesting and beautiful dwaf swordtail is the Xiphophorus multilineatus. This dwarf is endemic to the Rio Choy of Rio Pánuco basin in San Luis Potosi in Mexico.

These swordtails will reach up from 4 cm to 5cm of length. That's just body length and the swordtail is not included yet. females tend to grow up a bit more in comparison to the males. If we look at the appearance of the females, they do have similarities to the females of the X.pygmaeus and X.continens.

Above: An adult couple.

Above: An adult male.
Below: An adult female.

Best kept at moderate temperatures 22°C-25°C.
In some way there are very different visions on how hard they seem to reproduce. I myself haven't had any problems to get them to breed. To me it seemed that they reproduced easily. The offspring will look like the mother when it comes to their phenotype.
The gestation itself may take 3-4 weeks and an average batch of 5-15 fry will be born.

Above: A few weeks old fry.
Once the juvenile males will show their gender, the males will slowly change their colors and bodyshape. The horizontal stripe pattern will dissappear. And a lateral line which is edged shaped will remain on both sides. By the way, also the females will have such a lateral line. But depending on their mood and how the light will refelct their bodies, you'll be able to see more horizontal lines (which are not edged shaped).
The males will develop a yellow-orange coloration in the dorsal and caudal.

Above: Two adult males.
Below: Two adult couples.

They prefer some water flow in the tank. So, be sure to give them that.

Xiphophorus nezahualcoyotl

The Xiphophorus nezahualcoyotl is also called Mountain swordtail or Northern mountain swordtail. Among keepers of this strain, they're also known as "Nezzies". The name "Nezahualcoyotl" means "hungry coyote". And this strain was named after an acolhuan philosopher, ruler and warrior by the name of Acolmiztli Nezahualcoyotl (☼1402 - †1472).

This sport inhabits fast till moderate flowing creeks in mountainous areas which are parts of the Rio Tamasi drainage (state of San Luis Potosi, Mexico).

Above: An adult male.
Below: An adult female.

This swordtail won't become that large and could be considered a dward swordtail as well. Average size of an adult male will be about 5 cm (sword not included). And an average size of a female will be 5-6 cm.

Xiphophorus Alvarezi

This swordtail is also called "Chiapas swordtail".
The X.alvarezi occurs in Rio Santo Domingo in the state of Chiapas in Mexico and Huehuetenango, El Quiche and Alta Veracruz in Quatemala.

This species is not the most easy swordtail there is. It might take a while before they'll reproduce themselves. In my opinion, is to leave those fish on their own for a while. Only observing and nothing more. In some way, they have to get adjusted to their enviroment all by themselves. Be sure that there's some water movement to make them more comfortable. 


Xiphophorus helleri yucatan

Another great wildstrain of swordtail is the Xiphophorus helleri yucatan. It's a swordtail which can grow up explicit larger than the average swordtail. 

This strain is from the Yucatán peninsula (Mexico). It concerns also a green swordtail (don't take "green" too literally) and as already been mentioned they do grow up large. There's one specific stripe on both sides of the body which shows very clear. This stripe is winered colored. But with dominant males you'll hardly see this stripe on each side. This is because dominant males tend to get a red or orange color which covers the whole lower part of the body which will cover the winered stripe.

Above: An adult female. The winered stripe is explicit present.
Below: An adult male. This is clearly a dominant male. 

These swordtails are highly profilic and even those fry already show a ferm body build. About eating their own fry is something I hear several stories about. But I honestly do have to mention that my experience with these fish is that fry won't be eaten. I just leave those fry in the open with those adults.

They do well at lower temperatures and for sure suitable to keep outdoors when the temperatures will allow it. I'd like to categorize this strain as being easy to keep.

Xiphophorus montezumae

The Xiphophorus montezumae ia also known as Montezuma swordtail.
The distribution of the habitats of this strain ranges from Rio Tamesi, Tamaulipas, Northern Veracruz and San Luis Potosi in Mexico.

Depending on the location, the specimens tend to look differently. Most wellknown version is the one with the typical black markings on their bodies. Both genders "can" have those spots but it seems that males tend to have more black markings in general in comparison to the females. Just a small number has some tiny black markings but most females don't have them.  But the amount of black markings also differ from where the original versions came from (so the locality where the originals were caught).
The picture below shows a male which hardly shows black markings (just some tiny spots).

Something which is also very typical with montezuma swordtails is that you definitely know if you have a female or male when they're almost hitting adulthood. Late males do occur very often with this kind of swordtails as well. Also a clear gravid spot is not present with each female. 

It's a very vivid type of swordtail. Which means that they also need sufficient space to swim. Especially when males try to compete with another to see which might be the most dominant male, you need to give them the space they need.

And it's not just because of their vividness that these swordtails need a large tank but it's also because of the sword which a male will develop. For this kind of swordtail will develop one of the largest swords of most known swordtails.
Above:Two beautiful males.

Xiphophorus helleri Rio Papaloapan

Another green wild form of swordtail is the Xiphophorus helleri Rio Papaloapan. This speckled type of green swordtail occurs in the Rio papaloapan stream in (state of Veracruz) Mexico.

This is one of the most way easiest wild strains there is. Thusfar is seems that they do well in a wide range of waterparameters. Even when it comes to reproduction they seem one of the most profilic ones. It also seems that they have a shorter gestation than other wild swordtails. My own experience shows an average gestation of 3 weeks. And the fry also grows up faster than most.  I do keep them at low temperatures and even with those rates they reproduce fast. 
Most fry show speckles already at an early stage. But the amount of body speckles do differ from fish to fish. 

Above: A beautiful male specimen.
Below: An adult female.

This is an average sized swordtail which has a lack of dominant behaviour in a tank unlike a lot of other swordtail strains. Which makes this kind a good contender for a community tank.

Xiphophorus helleri pearl white

Besides wildstrains, I also do keep and breed fancy strains. One of them is the white swordtail. Although white swordtail strains already exsist, it's a bit hard to get your hands on some where I'm located. So, I've decided to create my own whites.

I've used blue swordtails with koi (kohaku) swordtails back in 2015. It took a while before I had real whites. The male above and below does show some orange in its gonopodium (a left over from the koi swordtails). 

Below: One of the couples which shows already a lot more white (January 2016).

I've started culling those most white offspring to accomplish my goal.

Below: A juvenile white female which is developing perfectly.

Below: A picture of a male (January 2016) with still some blue and some orange. But most of those markings has dissappeared till the final whites occured.

Thusfar the strain seems steady and it turned out that those females can grow up pretty large. 

Above: two white juveniles.

Xiphophorus helleri red velvet

I do love red swordtails, despite of the fact that they're fancy swordtails. But the red velvet version is the one I love most. This red is darkred and yes, the skin looks like velvet.

These swordtails do grow up large and they've got a ferm body build. I do have to say that dominance among both males and females do occur very often with this kind.
They need a lot of space to develop a good bodysize. They're also very profilic and batches of 50-80 fry seems normal. and what's also remarkable is that they won't eat their fry. At least, by my own experience these adults will leave their offspring alone. 
Below: An adult female with a bunch of fry (my ap;ologies for the blurred picture).

Above: an adult male with a good shaped body. It does show a healthy appearance.
Below: Two pictures of clearly wellbuilt red velvet swordtails.


This hi-fin swordtail seems to be a chinese cross just like his cousin the "sabertail". The difference between the standard cauliflower and the sabertail is that the sabertail has got a saber shaped sword. The name "cauliflower" itself refers to the shape of the elongated dorsal of both genders. But the female has got a less elongated dorsal in comparison to the male.

It's got a sturdy build bodyshape, which is quite unique for a swordtail fish. In my opinion the bodyshape reminds me of a mix of swordtail and molly.
They're red eyed which would make them suitable for a tank with dimmed light. Most albinos and lutinos are sensitive to bright light.
Among fancy swordtails, this sports is a majestic one. Its whole appearance shows class, strength and respect.

Above: An adult male.
Below: An adult female.

Below: Even from the top they look majestic.

Xiphophorus variatus La laguna

This wildstrain can be found close to the east coast of Mexico (state of Tamaulipas). The habitats has got a wide range from southern Tamaulipas, eastern San Luis Potosi and northern Veracruz. In general they inhabit  slow flowing till still waters.

This species does well at lower temperatures and after an average gestation a female will drop between 5-20 fry in general. Good thing is that also this strain will leave their newborn fry at ease. So, creating a colony without a threat of fry eating is potential. 

Despite of the fact that males tend to become very colorful, it will take quite long before a male will have its final colors. But not all males will be that bright colored. For it's mostly the dominant males which will become the best colored specimens within the colony. Females don't have that much color but they're well-speckled for that matter. And some females do tend to have somewhat yellow in their fins.

Above: A juvenile male which is starting coloring up.

Xiphophorus evelynae

A wildstrain platy close related to the Xiphophorus variatus is the Xiphophorus evelynae. This strain is also known as Highland platy.
This platy is mainly found in the Rio Tecolutla stream.

This species prefers densely vegetated tanks to hide and sufficient swimming space for they tend to be vividly. Despite of their vividness, they're real friendly fish. 

In general they're greyish till lightbrown bodied with some spots on their body. They do show some yellow in their fins.

Above: An adult male.
Below: Two adult females.

It's a profilic kind of fish which doesn't seem to chase their fry. Also with this strain I do keep the new offspring with the adult fish. 
While doing well at lower temperatures makes this a very easy to keep type of fish. A real good contender to keep outdoors during spring and summer.  

Xiphophorus xiphidium

This species mentioned is also called "One spot platy".
This platy is endemic to Rio Santa Engracias at Tamaulipas in Mexico. It's a platy which has got a short bottomsword unlike other platies. It's a vey easy and hardy fish to keep. The name "One spot"seems very obvious in this case.
When males age they tend to get a hump on their backs and tend to develop a pseudo gravid spot. Further on they can also develop a couple of vertical bars on both sides of their body. Males size up to 4cm and females up to 5 - 6cm.
Below: A juvenile couple of Xiphophorus xiphidium.

The one spot strain which I'm keeping came from a generation wild caught fish in 1978. And there was no influence of other platy strains involved.

Above: An adult female and a juvenile male (the anal fin is already changing into a gonopodium)
There are also two other variations of the Xiphophorus xiphidiumcalled "Two spot platy" and "Crescent platy". The two spot platy is to be found in Rio Purification and the crecent platy in branches of Rio Soto La Marina.

Xiphophorus milleri

This platy is also called "Catemaco platy".
This species is endemic to the Papaloapan ecoregion (state of Veracruz)  in Mexico. This platy occurs in shallow tributaries of Lake Catemaco and in shallow mouths (brackish water) of inlets along the shoreline.

It's a yellow bronze bodied paty with speckles and mostly a crescent mark at the rear. There's a real difference in body build in comparison to the xiphophorus maculatus. 
There are also darker bodies males which seem to be also smaller than their bronze coloured relatives. Those darker bodied ones came to adulthood too fast (determined on the Y-chromosone). While regular males size up to approx. 4cm, these dark males will size up to approx. 2,5cm. Females however can size up to 5cm.

After a gestation of 3,5 - 4 weeks a number of fry will be born between 10 - 40. The adults will hardly chase their offspring.