{"id":870,"date":"2019-06-25T11:06:09","date_gmt":"2019-06-25T11:06:09","guid":{"rendered":"http:\/\/www.britishlivebearerassociation.co.uk\/site\/?p=870"},"modified":"2022-05-16T06:33:28","modified_gmt":"2022-05-16T06:33:28","slug":"the-northern-swordtails","status":"publish","type":"post","link":"https:\/\/www.britishlivebearerassociation.co.uk\/site\/2019\/06\/25\/the-northern-swordtails\/","title":{"rendered":"The Northern swordtails"},"content":{"rendered":"\n

The northern swordtails live in and around the Panuco river basin and are separated from the southern swordtails by a geographical dividing line known as the Trans-Mexican volcanic belt. The northern swordtail group is made up of three clades and these are the Montezumae clade, the Cortezi clade, and the Pygmaeus clade.<\/p>\n\n\n\n

Please click on the title of the fish to see the profile<\/p>\n\n\n\n

The Montezumae Clade<\/strong><\/p>\n\n\n\n

Xiphophorus montezumae<\/a><\/strong><\/em><\/p>\n\n\n\n

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Xiphophorus nezahualcoyotl<\/a><\/em><\/strong><\/p>\n\n\n\n

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Xiphophorus continens<\/a><\/em><\/strong><\/p>\n\n\n\n

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The Cortezi clade<\/strong><\/p>\n\n\n\n

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The Cortezi clade consists of three species X. cortezi, X. birchmanni <\/em>and X. malinche <\/em>and are regarded by many as some of the most beautiful fish within the Xiphophorus Genus. The swordtails themselves are medium sized swordtails and grow about 50 \u2013 60 mm in length. They are not too difficult to maintain and they lend themselves to planted community aquariums as well as species only set ups.<\/p>\n\n\n\n

Xiphophorus cortezi<\/a><\/em><\/strong><\/h4>\n\n\n\n
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The Cortes sword has many populations with\nsome of them having males that have striking bright yellow dorsal and caudal\nfins with a body sporting a series of thin vertical stripes. The Cortes sword\nhas the largest distribution of the clade which ranges from just south of the\nRio Tampaon \u2013 Santa Maria axis to parts of the Rio Claro and tributaries of the\nRio Calabozo. Within this range they can be found at altitudes of between 100\nmetres to 1200 metres although they are reportedly more prevalent at the lower\naltitudes. The habitat they are found in is generally free of vegetation and\nfast flowing.<\/p>\n\n\n\n

Xiphophorus birchmanni<\/a><\/em><\/strong><\/p>\n\n\n\n

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The birchmanni swordtail is also known by\nthe common name of the \u2018sheepshead\u2019 swordtail. This reason for this common name\nis due to the large prominent bump that forms at the back of the head of mature\nmales giving a similar profile to that of a sheepshead! The dorsal and caudal\nfins are a beautiful yellow colour which are scattered with a covering of small\nblack spots. The caudal fin is most unusual as it doesn\u2019t grow a sword or if it\ndoes it remains very small, but the dorsal fin (seemingly trying to compensate\nfor the failing of the caudal fin) grows quite large in contrast and becomes\nalmost sail like in appearance. The body shape is generally deeper than that of\nthe others members of the clade and the flanks also show a series of  vertical stripes similar to those of the\nCortes sword apart from being distinctly much broader.<\/p>\n\n\n\n

The distribution of the birchmanni\nswordtail is also fairly extensive, ranging from the Rio Sans Pedro down to the\nRio Tuxpan drainage incorporating the Rio Vinazco and the Rio Beltran. This\nspecies of swordtail is generally found at higher altitudes than the Cortes\nsword and has been found between the altitudes of 500 and 1000 metres. This\nspecies is generally found in a habitat of fast flowing water over a rocky \/\nsandy substrate with dense vegetation. <\/p>\n\n\n\n

Xiphophorus malinche<\/a><\/em><\/strong><\/p>\n\n\n\n

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The malinche swordtail also grows a lump\nbehind the head in the same fashion as the birchmanni swordtail, but this is\nnot anywhere near as prominent. The colouring is similar to that of the\nbirchmanni swordtail with a distinctive yellow caudal with a medium sized sword\nand yellow dorsal fin showing black spots. The body colour is also similar but\ndoes seem to have purple hue. Unlike the previous clade members the stripes on\nthe flanks of the malinche swordtail are far more irregular, often at different\nangles to each other and sometimes broken in appearance.<\/p>\n\n\n\n

The range of distribution for the malinche\nswordtail is at present relatively small due to the fact it has not yet been\nfully explored. Their current range includes the Rio Claro down to the\ntributaries of the Rio Calabozo.<\/p>\n\n\n\n

The common name for the malinche swordtail\nis the Highland swordtail. This name derives from the altitude of the rivers\nand streams they inhabit. They are found at altitudes which range from 650 to\n1300 metres. The habitat they can generally be found in is one of fast flowing\nwater over a sandy substrate with dense vegetation.<\/p>\n\n\n\n

The three species overlap within their\nrespective ranges and hybrid populations do exist. Where the Cortes swordtail\noverlaps with either the birchmanni swordtail or the malinche swordtail it is\nat the higher end of the Cortes swordtail range and lower end of either the\nbirchmanni or malinche swordtail range. Similarly when the birchmanni swordtail\nand the malinche swordtail ranges overlap it is at the higher end of the\nbirchmanni swordtail range and lower end of the malinche swordtail range.<\/p>\n\n\n\n

It is unfortunate that in recent times, the\nmembers of this clade apart from X.\ncortezi<\/em> have been absent from the UK side of the hobby. Happily I am\npleased to say that at recent events birchmanni swordtails have started to make\na comeback and are already becoming more sought after. This is a trend that I\nhope will continue, and with luck (fingers crossed), malinche swordtails will\nalso make a welcome return to the UK.<\/p>\n\n\n\n

The\nPygmaeus clade <\/strong><\/p>\n\n\n\n

The Pygmy swordtails are as the name\nsuggests some of the smallest swordtails known within our hobby. The Pygmy\nswordtails form the Pygmaeus clade which is made up of three species (Xiphophorus\npygmaeus<\/em>, Xiphophorus nigrensis<\/em>\nand Xiphophorus multilineatus<\/em>), the three species live in the state\nof Sans Luis Potosi within the Rio Panuco river basin. The rivers these\nswordtails are predominately found in are the Rio Huichihuayan (Xiphophorus pygmaeus<\/em>), the Rio Choy (Xiphophorus nigrensis<\/em>) and the Rio Coy (Xiphophorus multilineatus<\/em>). These rivers\nare formed in close proximity to each other by natural springs that surface in\nthe Sierra Madre Mountains and although the rivers are formed and run closely\nto each other, there are no natural connections between any of them.<\/p>\n\n\n\n

Xiphophorus pygmaeus<\/a><\/em><\/strong><\/p>\n\n\n\n

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The pygmy swordtail is as the name suggests\nthe smallest of the clade reaching a length of 30mm for males and 40mm for\nfemales. This species is well known within our hobby with many of us at one\ntime or another keeping either the blue or yellow form, at the auctions this\nspecies is usually well represented and always popular.<\/p>\n\n\n\n

The type locality for the pygmy swordtail\nis the Rio Axtla which was described as being a fast flowing river with little\nvegetation. This description was as you would expect with the information given\nbecame the model for how most aquarists kept this species for many years.\nSubsequent research has now shown that the pygmy swordtail is generally found\nin highly vegetative areas of slow moving water away from the main currents.\nThese new findings have since altered the preferred method of maintenance to a\nwell planted aquarium with moderate to little water movement.<\/p>\n\n\n\n

The pygmy sword is found predominately in\nthe Rio Huichihuayan, but they can also be found to a lesser extent in both the\nRio Tancuilin and the Rio Axtla. The Rio Huichihuayan and the Rio Tancuilin\nmerge together to form the Rio Axtla.<\/p>\n\n\n\n

Xiphophorus nigrensis<\/a><\/em><\/strong><\/p>\n\n\n\n

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The El Abra swordtail (Xiphophorus nigrensis<\/em>) is only found in the Rio Choy, a deeper\nbodied fish than the pygmy sword with the larger type males reaching a standard\nlength of 40mm with a sword of up to 30mm long. This species not always\navailable at the auctions these days, however if you can provide the correct\nconditions for these fish, they are definitely worth keeping.<\/p>\n\n\n\n

The River Choy originates from a cave\nwithin the El Abra Mountain giving this swordtail its common name of the El\nAbra swordtail. The El Abra swordtail is found along most of the length of the\nriver but is most prolific nearest to the source. The population density\ndecreases the further downriver you go and is not found where the Rio Choy\njoins the Rio Tampoan on its northern side.<\/p>\n\n\n\n

The\nbody colouration is greyish blue with a single bold zigzag midlateral line, in\nfully mature males the colour becomes more of an intense metallic blue and the\nmidlateral line fades out. The males for X nigrensis<\/em> have three size variations\nwith the larger type male being the one most commonly found in the hobby. There\nare two main reasons that I can see for this, the first reason from a selfish\npoint of view being that they are the better looking fish with the best\ncolours. The second reason is a lot more understandable, in the wild the\npresence of larger type males is maintained due to them being bigger than the\nother males, this allows them the more prominent areas with which to attract\nthe females. Swordtail females (according to some of the studies I have read)\nfor their part are more amenable to mate with the larger males. However in the\naquarium the smaller males mature more quickly and are therefore able to mate\nat a much younger age, this if left unchecked would create an aquarium\npopulation with only smaller type males, the larger type would disappear from\nthe hobby.<\/p>\n\n\n\n

This species is renowned for being\ndifficult to maintain, they are highly susceptible to changes in water\nconditions particularly P.H. and with this in mind water changes should be\nfrequent and small, a well planted aquarium with hard water and good filtration\nis undoubtedly the best environment to maintain them.<\/p>\n\n\n\n

Xiphophorus multilineatus<\/a><\/em><\/strong><\/p>\n\n\n\n

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Xiphophorus multilineatus<\/em> is found in the Rio Coy\nand some parts of the Rio Tampoan. The Rio Coy is mainly formed from the waters of\ntwo springs, (the Arroyo Tambaque, and the Arroyo Oxitipa). Having a very\nsimilar description to the Rio Choy in being a fast flowing river with\nrocky habitats near the source and muddy\/sandy substrates with dense vegetation\nin the slower areas. Xiphophorus multilineatus<\/em> is found along\nthe entire length of the river which is also a tributary to the Rio\nTampoan but this time on the southern side.<\/p>\n\n\n\n

Xiphophorus multilineatus<\/em> is a similar looking\nspecies to Xiphophorus nigrensis<\/em> and\nwas often confused as such in early collections. In 1979 it was believed to be\na separate population of X. nigrensis<\/em> which I believe was\nresponsible for the description being so much later than the initial\ncollection. Xiphophorus multilineatus<\/em> does have two major differences that\nseparates it from X. nigrensis,<\/em>\nthe first being the stripes on the flanks of the males (this is where the name\nmultilineatus comes from) and the second is the high back which forms on mature\nmales somewhat similar to Xiphophorus\nbirchmanni<\/em>.<\/p>\n\n\n\n

This\nspecies also has different size variations for males, the\nlarger males develop a high back and vertical barring on the flanks. All males\nhave a body colouring of pale metallic blue and a single bold zigzag midlateral\nline. As with the El Abra sword the\nlarger type males are the ones most known within the hobby. <\/p>\n\n\n\n

This is a shy species that requires a high\nlevel of vegetation in which to hide, although not as easily upset as X. nigrensis<\/em> with water changes, the\nsame routine is probably best followed. Water changes should therefore be\nfrequent and small, the aquarium should be well planted aquarium with hard\nwater and good filtration along with aeration.<\/p>\n\n\n\n

Again this species is not as frequently\nseen at the auctions as it once was, these are lovely fish to keep and again\nalso worth keeping.<\/p>\n","protected":false},"excerpt":{"rendered":"

The northern swordtails live in and around the Panuco river basin and are separated from the southern swordtails by a geographical dividing line known as the Trans-Mexican volcanic belt. The northern swordtail group is...<\/p>\n","protected":false},"author":59,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-870","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/www.britishlivebearerassociation.co.uk\/site\/wp-json\/wp\/v2\/posts\/870","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.britishlivebearerassociation.co.uk\/site\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.britishlivebearerassociation.co.uk\/site\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.britishlivebearerassociation.co.uk\/site\/wp-json\/wp\/v2\/users\/59"}],"replies":[{"embeddable":true,"href":"https:\/\/www.britishlivebearerassociation.co.uk\/site\/wp-json\/wp\/v2\/comments?post=870"}],"version-history":[{"count":16,"href":"https:\/\/www.britishlivebearerassociation.co.uk\/site\/wp-json\/wp\/v2\/posts\/870\/revisions"}],"predecessor-version":[{"id":3914,"href":"https:\/\/www.britishlivebearerassociation.co.uk\/site\/wp-json\/wp\/v2\/posts\/870\/revisions\/3914"}],"wp:attachment":[{"href":"https:\/\/www.britishlivebearerassociation.co.uk\/site\/wp-json\/wp\/v2\/media?parent=870"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.britishlivebearerassociation.co.uk\/site\/wp-json\/wp\/v2\/categories?post=870"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.britishlivebearerassociation.co.uk\/site\/wp-json\/wp\/v2\/tags?post=870"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}