Pencil fish

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Pencilfish
Nannostomus.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Characiformes
Family: Lebiasinidae
Subfamily: Pyrrhulininae
Tribe: Nannostomini
Genus: Nannostomus
Günther, 1872
Type species
Nannostomus beckfordi
Günther, 1872

Nannostomus (from the Greek nanos = small, and the Latin stomus = relating to the mouth) [1] is a genus of fish belonging to the characin family Lebiasinidae. All of the species in this genus are known as pencil fish, a popular name that was initially only applied to two species in the 1920s, Nannostomus unifasciatus and Nannostomus eques, by the late 1950s however, the term would be applied to all members of the genus. [1] [2] [3] Several species have become popular aquarium fish due to their attractive coloration, unique shape, and interesting demeanor.

Contents

Taxonomy

The genus Nannostomus was first described by Günther in 1872 with the type species, N. beckfordi . In 1876, Steindachner described three more species, N. unifasciatus , N. eques (pictured below), and N. trifasciatus (pictured above). In 1909, Carl H. Eigenmann described N. marginatus , N. minimus , N. erythrurus and N. harrisoni . Several of these have been popular with aquarists since the early 20th century, partly due to enthusiastic articles written about them and photographs taken by William T. Innes that were published as early as 1933. Over the years, the genus was split by subsequent authors into other genera, including Poecilobrycon and Nannobrycon. After nearly a century of debate on the subject, Dr. Stanley Howard Weitzman and Dr. J. Stanley Cobb restored earlier taxonomy and expanded upon it, unifying all species under Nannostomus in 1975. [4] This comprehensive revision of the genus has now been widely accepted. Dr. Weitzman is also responsible for describing five of the more recently introduced species, N. marilynae , N. limatus , N. nitidus , N. britskii and N. anduzei . [5] Twenty species are now known, most of which are also familiar to aquarists. Several other unidentified Nannostomus species have been imported over the years; many were found as bycatch with other small characins, but their taxonomic status is yet to be determined.

Species

The 20 currently recognized species in this genus are: [6] [7]

Description

Nannostomus eques (brown pencil fish, Diptail) Nannostomus eques.jpg
Nannostomus eques (brown pencil fish, Diptail)

Most species are slender, pencil-shaped fish ranging in size from under 1–2 in long (2.5–5.1 cm). N. marginatus, N. rubrocaudatus, and N. mortenthaleri possess shortened, blockier outlines reminiscent of pencil stubs. [1] All but one species, Nannostomus espei, possess one to five horizontal black or brown stripes with gold or silver iridescence appearing above the primary stripe. Most also display red, orange, or maroon highlights on their fins, and many have flashes of these colors on their bodies as well. The recently described N. mortenthaleri and N. rubrocaudatus are especially vividly colored. N. espei is unique in that the horizontal stripes are only weakly present and are supplanted by five dark comma-shaped blotches. Other species take this appearance at night, but only N. espei displays the pattern permanently and in daylight. [9] The adipose fin is present in some species and absent in others, while in certain species, such as N. eques, its presence or absence varies between individuals. All species swim horizontally, except N. unifasciatus and N. eques, which assume an oblique, 'snout-up' posture. [1]

Sexual dimorphism occurs in the genus to varying degrees. In some species the males are more brilliantly colored, especially the fins. In other species dimorphism is far less evident. However, the anal fin is generally a reliable indicator of gender. For most species the anal fin of adult males is enlarged and elongated (as in N. espei, N. eques, etc.) and/or more colorful (as in N. harrisoni, N. marginatus, etc.). The popular aquarium species, N. trifasciatus, is an exception in this regard.

Distribution

The genus as a whole has a vast distribution in South America, from Colombia, Venezuela, and the Guyanas in the north, to the southern Amazon basin and Bolivia in the south, to Peru in the west, and Belém, Brazil, in the east. [4] Several of the individual species have a distribution nearly as vast. As a result, many of the species are polymorphic and manifest marked color variations depending on the population. Over the years, some of these color variants have been erroneously described as separate species. Such names as 'Nannostomus ocellatus', 'N. anomalus' and 'N. auratus', among many others, are now known to be junior synonyms for the various species.

In the aquarium

To date, only two species, N. beckfordi and N. harrisoni, have been commercially raised for the aquarium trade in fisheries, mostly in Asia. All of the remaining species that find their way to home aquaria are wild-caught from South American waters. Nannostomus species thrive in home aquaria when provided with soft, moderately acidic water, low nitrate levels, and temperatures in the range of 22–28 °C (72–82 °F). The addition of aquatic plants is recommended, including floating varieties as they reduce the likelihood of fish jumping, a common occurrence for some of the species, especially N. espei and N. unifasciatus. They should be kept in schools of at least six, or in a community aquarium with other species of Nannostomus, other small peaceful characins, or corydoras. Aquariums with a strong water current, large tankmates, or swift-moving species should be avoided. If kept in a thickly planted single-species aquarium with the above water parameters, most species will spawn, eggs will not be eaten, and fry will be found growing in the floating plants. Baby brine shrimp, live or frozen, and other small-sized foods are required for both fry and adults. [1] They are also avid biofilm grazers and, for most of the species, algae are under-reported staples of their diet. In most species, the males establish small territories and defend them. Their defensive actions are usually harmless, but in two species, N. mortenthaleri and N. trifasciatus, antagonistic behavior directed at conspecifics can be harmful if sufficient space and plant cover is not provided. Once acclimated to the aquarium and provided with suitable conditions, they are hardy, often living for five or more years. [9]

Related Research Articles

<i>Hyphessobrycon</i> Genus of fishes

Hyphessobrycon is a genus of freshwater fish in the family Characidae. These species are among the fishes known as tetras. The genus is distributed in the Neotropical realm from southern Mexico to Río de la Plata in Argentina. Many of these species are native to South America; about six species are from Central America and a single species, H. compressus is from southern Mexico.

<i>Copella</i> (fish) Genus of fishes

Copella is a genus of freshwater fish belonging to the family Lebiasinidae, native to South America, known colloquially to aquarists as splashing tetras or splash tetras, because of the unique reproductive method of the best-known representative of the genus, Copella arnoldi. They are not as closely related to the tetras proper in the Characidae as initially believed.

<span class="mw-page-title-main">Glandulocaudinae</span> Subfamily of fishes

Glandulocaudinae are a subfamily of tropical freshwater characin fish from Central and South America. In all species of this subfamily, a gland on their caudal fin is found almost exclusively in the males, which allows the release and pumping of pheromones; also, members of this subfamily have complex courtship behaviors which lead to insemination. The ecology and life history of these fish is complex yet little studied. Glandulocaudines are important as food fish for larger fish important for commercial and subsistence reasons.

<i>Nannostomus trifasciatus</i> Species of fish

Nannostomus trifasciatus,, commonly known as the three-lined or three-stripe pencilfish, is a freshwater species of fish belonging to the characin family Lebiasinidae. They are popular in the aquarium trade due to their small size, beautiful color pattern, and relative hardiness.

Nannostomus harrisoni,, is a species of pencil fish. Native to The Guianas, the species displays a single horizontal stripe of intense black, and blood red adornments on its fins. N. harrisoni is often confused with Nannostomus unifasciatus, another long, slender, single-striped species with similar profile and coloration, but N. harrisoni swims in a horizontal posture, as opposed to the snout-up oblique posture of N.unifasciatus, and the bright red adornments on the ventral fins of N. harrisoni are absent in N. unifasciatus. Though the recently described species N. grandis has been dubbed the largest member of the genus, adults of N. harrisoni commonly grow to a length of 70 mm, making it in fact the largest species of pencil fish described to date. It is commonly known as Harrison's pencilfish.

<i>Moenkhausia</i> Genus of fishes

Moenkhausia is a genus of freshwater fish in the family Characidae native to tropical and subtropical South America. These are medium-sized tetras where the largest species only reach around 12 cm (4.7 in).

<i>Hemigrammus</i> Genus of fishes

Hemigrammus is a genus of freshwater fish in the family Characidae native to South America and commonly seen in the aquarium trade. These are medium-small tetras where the largest species reach up to around 11 cm (4.3 in).

Knodus is a genus of characins, small freshwater fish from South America.

<i>Pyrrhulina</i> Genus of fishes

Pyrrhulina is a genus of freshwater fishes found in tropical South America. Several of these species are popular aquarium fish.

<i>Nannostomus anduzei</i> Species of fish

Nannostomus anduzei is a freshwater species of fish belonging to the genus Nannostomus in the characin family Lebiasinidae. It is native to Venezuela and northern Brazil, particularly the upper Orinoco and Rio Ererê, a tributary of the Rio Negro. The adults grow to a maximum length of only 16 mm, making them one of the smallest pencilfish. Other common names include miniature pencilfish, miniature nannostomus, and Anduzi's nannostomus.

Nannostomus grandis is a freshwater species of fish belonging to the characin family Lebiasinidae. This species is closely related to Nannostomus beckfordi, being somewhat similar in coloration, but with a more elongated body. It has been described as the largest member of the genus; however, N. harrisoni consistently reaches a mature length in excess of 60 mm and is the more likely claimant for that distinction. It was only recently formally described by Zarske, although the author reports it probably had been assumed to be a form of N. beckfordi in the past and had even been exported for the aquarium trade at times. It is native to Brazil and currently has no accepted common name.

Nannostomus britskii,, commonly known as the spotstripe pencilfish, is a freshwater species of fish belonging to the family Lebiasinidae of characins. They were first described in 1978 by Stanley H. Weitzman along with two other new species, from a collection of specimens preserved in the São Paulo museum. They have been recorded from only two localities, both in Brazil. No live specimens had been seen, collected, or exported for the aquarium trade until very recently.

Nannostomus digrammus,, commonly known as the twostripe pencilfish, is a freshwater species of fish belonging to the characin family Lebiasinidae. They were first described in 1913 by Henry Weed Fowler and are fairly typical of members of this genus being small, elongated fish with prominent horizontal stripes, in this case limited to two dominant stripes, usually maroon in color. They are recorded as native to Brazil and Guyana, where they occur fairly widely, but are seen only occasionally in the aquarium trade.

<i>Nannostomus eques</i> Species of fish

Nannostomus eques,, commonly known as the diptail,brown or hockey stick pencilfish, is a freshwater species of fish belonging to the characin family Lebiasinidae. It was first described in 1876 by Franz Steindachner making it one of the first members of the genus to be discovered and described. It is fairly typical of members of this genus being a small, elongated fish with prominent horizontal stripes. It occurs quite widely in South America, having been recorded in Brazil, Peru, Colombia, and Guyana. It is also quite commonly met with in the aquarium trade where its habit of swimming and posturing at a 'snout-up' angle—one of two Nannostomus species to do so, the other being Nannostomus unifasciatus—makes it a popular choice.

<i>Nannostomus espei</i> Species of fish

Nannostomus espei,, commonly known as Espe's pencilfish or barred pencilfish, is a freshwater species of fish belonging to the characin family Lebiasinidae. It was first described in 1956 by Herman Meinken from the Mazaruni River system in Guyana and to date this is its only known location. It is notable amongst the genus in that the dominant body pattern consists of five broad, comma-like patches instead of the more normal horizontal stripes seen in the rest of the genus. This pattern of patches is assumed by other species at night, but only N. espei displays the pattern permanently and in daylight.

<i>Nannostomus limatus</i> Species of fish

Nannostomus limatus,, commonly known as the elegant pencilfish, is a freshwater species of fish belonging to the characin family Lebiasinidae. They were first described in 1978 by Stanley H. Weitzman along with two other new species, from a collection of specimens preserved in the São Paulo museum. Only rarely imported and kept by aquarists, they have been recorded from the Amazonian region of Brazil, specifically near Santarém.

<i>Nannostomus marginatus</i> Species of fish

Nannostomus marginatus,, commonly known as the dwarf pencilfish, is a freshwater species of fish belonging to the genus Nannostomus in the characin family Lebiasinidae. They were first described in 1909 by C. H. Eigenmann and are typical of members of this genus being small, elongated fish with prominent horizontal stripes. The most notable feature of N. marginatus is its size, it being one of the smallest members of the genus, only reaching a maximum size of 35 mm. They occur widely on the South American continent having been recorded in Brazil, Guyana, Colombia, Suriname, and Peru, and have been a popular aquarium species since their introduction to aquarists in the early twentieth century.

<i>Nannostomus mortenthaleri</i> Species of fish

Nannostomus mortenthaleri, commonly known as the coral red pencilfish, is a freshwater species of fish belonging to the characin family Lebiasinidae. It is one of the most colourful of the genus, being suffused with a bright coral red colouration over its entire body and fins, in striking contrast to its horizontal jet black stripes. It was originally described as a subspecies of Nannostomus marginatus, but it is now recognised as a species in its own right. Mature males have a thickened anal fin. Maximum length is 29mm.

<i>Nannostomus unifasciatus</i> Species of fish

Nannostomus unifasciatus,, commonly known as the one-lined pencilfish, is a freshwater species of fish belonging to the genus Nannostomus in the characin family Lebiasinidae. They are popular in the aquarium trade due to their small size, beautiful color pattern, unique swimming posture and relative hardiness. With its long, pencil-shaped profile, its single jet black stripe reminiscent of the graphite core of a pencil, and its eraser-colored caudal fin, this is the species for which the popular name, 'pencilfish', was first coined in the 1920s, later to be applied to all the species of the genus Nannostomus.

References

  1. 1 2 3 4 5 Innes, William T. (1935). Exotic Aquarium Fishes (First ed.). Philadelphia: Innes Publishing Co. pp. 157–162. hdl:2027/coo.31924003400623.
  2. Vorderwinkler, William (1965). Pencilfishes. Neptune, NJ: TFN Publications.
  3. Innes, William T. (November 1940). "Poecilobrycon unifasciatus". The Aquarium. Philadelphia: Innes Publishing Co.
  4. 1 2 Weitzman, Stanley H.; Cobb, J. Stanley (1975). "A Revision of the South American Fishes of the Genus Nannostomus" (PDF). Smithsonian Contributions to Zoology. 186. Retrieved 2023-07-08.
  5. Weitzman, Stanley H. (1978). "Three new species of fishes of the genus Nannostomus from the Brazilian states of Para and Amazonas (Teleostei, Lebiasinidae)". Smithsonian Contributions to Zoology. 263. Retrieved 2023-07-08.
  6. Froese, Rainer and Pauly, Daniel, eds. (2013). Species of Nannostomus in FishBase . April 2013 version.
  7. 1 2 Zarske, Axel (2013-08-29). "Nannostomus nigrotaeniatus spec. nov. – ein neuer Ziersalmler aus Venezuela (Teleostei: Characiformes: Lebiasinidae)". Vertebrate Zoology (in German). 63 (2): 125–137. doi: 10.3897/vz.63.e31417 . ISSN   2625-8498 . Retrieved 2023-07-08.
  8. Zarske, Axel (2011-12-13). "Nannostomus grandis spec. nov. – ein neuer Ziersalmler aus Brasilien mit Bemerkungen zu N. beckfordi GÜNTHER, 1872, N. anomalus STEINDACHNER, 1876 und N. aripirangensis MEINKEN, 1931 (Teleostei: Characiformes: Lebiasinidae)". Vertebrate Zoology. 61 (3): 266–283. doi: 10.3897/vz.61.e31152 . ISSN   2625-8498.
  9. 1 2 Weitzman, Stanley H. (1967-12-30). "Review of South American Characid Fishes of Subtribe Nannostomina". Proceedings of the United States National Museum. 119 (3538). Washington DC: Smithsonian Institution Press. Archived from the original (PDF) on 2008-08-04. Retrieved 2023-07-08.