{"id":890,"date":"2019-06-25T17:31:29","date_gmt":"2019-06-25T17:31:29","guid":{"rendered":"http:\/\/www.britishlivebearerassociation.co.uk\/site\/?p=890"},"modified":"2022-05-16T06:32:59","modified_gmt":"2022-05-16T06:32:59","slug":"xiphophorus-nigrensis-rosen-1960","status":"publish","type":"post","link":"https:\/\/www.britishlivebearerassociation.co.uk\/site\/2019\/06\/25\/xiphophorus-nigrensis-rosen-1960\/","title":{"rendered":"Xiphophorus nigrensis (Rosen, 1960)"},"content":{"rendered":"\n

Etymology:<\/strong><\/p>\n\n\n\n

Xiphophorus:<\/em> Greek, xiphos<\/em> meaning \u2018sword\u2019; Greek, pherein<\/em> meaning \u2018to carry\u2019<\/p>\n\n\n\n

Nigrensis:<\/em> Latin, nigri<\/em> meaning \u2018black\u2019; Latin, ensis<\/em> meaning \u2018to come from\u2019. <\/p>\n\n\n\n

First\ndescription:<\/strong><\/p>\n\n\n\n

Donn E. Rosen 1960.<\/strong><\/strong><\/p>\n\n\n\n

Middle-American poeciliid fishes of the\ngenus Xiphophorus<\/em>.
\nBull. Fla. St. Mus. Biol. Sci 5 (4): p 57-242.<\/p>\n\n\n\n

Synonyms:<\/strong><\/p>\n\n\n\n

Xiphophorus pygmaeus nigrensis Rosen, 1960<\/p>\n\n\n\n

Common\nname:<\/strong><\/p>\n\n\n\n

El Abra Pygmy Swordtail<\/p>\n\n\n\n

History:<\/strong><\/p>\n\n\n\n

Collected by D.E. Rosen, M.S. Gordon and M.\nGordon on January 19th<\/sup> 1957<\/p>\n\n\n\n

Group:<\/strong><\/p>\n\n\n\n

Xiphophorus nigrensis<\/em> is one of nine\nnorthern swordtails and belongs to the Pygmaeus clade consisting of consisting of X. pygmaeus<\/em>, X. nigrensis<\/em> and X. multilineatus<\/em>.<\/p>\n\n\n\n

Type Locality:<\/strong> <\/strong><\/p>\n\n\n\n

Nacimiento del R\u00edo Choy, San Luis Potosi,\nMexico. <\/p>\n\n\n\n

Distribution:<\/strong><\/p>\n\n\n\n

Only found in the Rio Choy.<\/p>\n\n\n\n

Habitat:<\/strong>
<\/p>\n\n\n\n

Found along the length of the Rio Choy,\nmore common at the mouth of the cave where the river originates from, the water\nat this point is clearer and the current stronger.<\/p>\n\n\n\n

The Rio Choy is also known locally as the\nRio Florido near the Cave. This river is the northern most tributary of the Rio\nTampoan <\/strong><\/p>\n\n\n\n

The biotope is clear & fast flowing\n& originates from inside a cave under the El Abra Mountain. The biotope\nfurther downstream is reportedly slower flowing with dense aquatic plant growth\nespecially near the banks.<\/p>\n\n\n\n

\"\"
Rio Choy, Rio Panuco basin, SLP, Mexico
Photo courtesy of Dave Macallister <\/strong><\/figcaption><\/figure><\/div>\n\n\n\n

Size:<\/strong><\/p>\n\n\n\n

Males 25 – 40 mm; females 40 mm.<\/p>\n\n\n\n

Distinguishing\ncharacteristics:<\/strong>A species with a three known size\nvariations within the male range, the largest variant is the one most often in\nthe hobby. X. nigrensis in its larger form is a small high backed form of\nswordtail with a deep body and a medium sized sword of roughly \u00bd – \u00be total body\nlength.<\/p>\n\n\n\n

Colour\/Pattern Variability:<\/strong> <\/p>\n\n\n\n

Males
There\nare three size variants ranging from 25mm to 40mm. The larger males tend to be\ndeeper bodied. The body colouration is greyish blue with a single bold zigzag\nmidlateral line, (present from birth) but in fully mature males the colour\nbecomes more of an intense metallic blue and the midlateral line will fade out.<\/p>\n\n\n\n

The\ncaudal spot is variable and when present really prominent on the large males. All\nother fins are generally clear. The sword length varies according to the size\nvariant, the largest males can have a sword length equal to the body length and\nthe smallest 1-2mm. The sword is distinctly upturned particularly when small, the sword has black edging and is clear except\non some individuals it can be yellow.<\/p>\n\n\n\n

The\ndorsal fin is generally clear, there is a black edge and a black band one third\nof the way up the fin.<\/p>\n\n\n\n

As\nwith all of the Pygmaeus clade a yellow form of male can be found. <\/strong>
<\/p>\n\n\n\n

Females<\/strong>:<\/p>\n\n\n\n

A basic body colour of greyish blue with a single bold zigzag lateral line. All fins are clear, but the dorsal fin has a faint black edge and a faint black band one third of the way up the fin.<\/p>\n\n\n\n

\"\"
Photo courtesy of Ivan Dibble, taken at BLA 2004 <\/strong><\/figcaption><\/figure><\/div>\n\n\n\n
\"\"
Photo courtesy of Dave Macallister <\/strong><\/figcaption><\/figure><\/div>\n\n\n\n

Behaviour:<\/strong><\/p>\n\n\n\n

Shy at first but will become bolder as the\ncolony expands.<\/p>\n\n\n\n

Husbandry:<\/strong><\/p>\n\n\n\n

The Aquarium should be well planted with\nfiltration and aeration.<\/p>\n\n\n\n

This species is very susceptible to P.H.\nswings so all water changes should be small but frequent.<\/p>\n\n\n\n

Breeding\nNotes:<\/strong><\/p>\n\n\n\n

Females drop on a monthly cycle. Brood\nsizes are relatively small being only 2 for smaller females & up to 20 for\nmore mature females. These females are thought to be fertile between 3 – 8\nmonths of age.
\nLarge morph males sex out at 5 months.
\nIt is important to remove virgin females from the brood & mate with the\nlarger form males as the small form will become dominant with the loss of the\nlarger form. Females are not affected by this sex-linked gene which is only\nknown in males.<\/p>\n\n\n\n

References:<\/strong><\/p>\n\n\n\n

Donn E. Rosen:<\/strong> <\/strong>Middle-American\npoeciliid fishes of the genus Xiphophorus<\/em>.        <\/p>\n\n\n\n

Rauchenberger, Kallman & Morizot:<\/strong> <\/strong>Monophyly and\nGeography of the Rio P’anuco Basin Swordtails (Genus Xiphophorus) with Descriptions\nof Four New Species                                              Derek and Pat Lambert: <\/strong>Platies and\nswordtails       <\/strong><\/p>\n","protected":false},"excerpt":{"rendered":"

Etymology: Xiphophorus: Greek, xiphos meaning \u2018sword\u2019; Greek, pherein meaning \u2018to carry\u2019 Nigrensis: Latin, nigri meaning \u2018black\u2019; Latin, ensis meaning \u2018to come from\u2019. First description: Donn E. Rosen 1960. Middle-American poeciliid fishes of the genus Xiphophorus. Bull. Fla. St. Mus....<\/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-890","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/www.britishlivebearerassociation.co.uk\/site\/wp-json\/wp\/v2\/posts\/890","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=890"}],"version-history":[{"count":5,"href":"https:\/\/www.britishlivebearerassociation.co.uk\/site\/wp-json\/wp\/v2\/posts\/890\/revisions"}],"predecessor-version":[{"id":3912,"href":"https:\/\/www.britishlivebearerassociation.co.uk\/site\/wp-json\/wp\/v2\/posts\/890\/revisions\/3912"}],"wp:attachment":[{"href":"https:\/\/www.britishlivebearerassociation.co.uk\/site\/wp-json\/wp\/v2\/media?parent=890"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.britishlivebearerassociation.co.uk\/site\/wp-json\/wp\/v2\/categories?post=890"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.britishlivebearerassociation.co.uk\/site\/wp-json\/wp\/v2\/tags?post=890"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}