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CACHORROS

Acestrorhyncin

Characid Species

Contribution and research by Frank Magallanes and Tom Lorenz

Common names: Cachorinho, Cachorro, Mopiye, Payala, Pejezorro, Pez cachorro, Pez zorro, Pike Characin, Moinge, Halatawéi, Halataway, Dagu fisi, Ueua, Wayabra, Zadoe, Freshwater Barracuda.

FROM FRANK MAGALLANES

Acestrorhyncinae might not be a monophyletic group as previously believed, Menezes (1983) compared the genus Oligosarcus (Günther, 1864) and their relationship with Acestrorhychus. Genus Acestrorhynchus are a homogenous tribe. Most of the species can be delineated by several external features, including snout length, coloration and maximum size. All the forms are ichthyophagous and require good, clean oxygenated water with a warm temperate between 23 - 28 C. I was fortunate to make some rare footage of A. falcatus breeding behavior several years ago. A copy of the raw footage was sent to Oregon State University in 1994.

On the left are stills of the event. The species spent quite a few  hours doing this type of  "dance".

IN THE AQUARIUM

As hobbyists, aquarists should know that they are jumpers and need a tight fitting lid. Also, they prefer open habitat as opposed to a well decorated tank. They're not aggressive, and they don't appreciate aggressive fish, however they eat fish up to 2/3rds their size. They also need a great deal of space (a tank at least 5 feet long) because they can and do kill themselves by running into the sides of aquaria.

To read more about the care of the Acestrorhynchus species click here.

Valid Species Information -2011

Acestrorhynchus altus (Menezes, 1969)

98-115 scales in the lateral line; 27-34 scale rows from lateral line to origin of dorsal fin, 15-18 from lateral line to origin of anal fin.

Acestrorhynchus briskii (Menezes, 1969)

A distinct black band on sides of body, from upper end of opercle to caudal base; anal fin rays v, 23-27; 92-103 scales is the lateral line; 18 scale rows from lateral line to origin of dorsal fin, 12 from lateral line to origin of anal fin.

Acestrorhynchus falcatus (Bloch, 1794) A. falcatus is commonly found in the aquarium trade and sometimes easily identified at young ages, by its two black spots (one behind opercle and the other at the caudal peduncle base), and bright red fins. The species is distributed in South America; Guyana, Amazon and Orinoco basins. The fish is known to grow at least 20 cm and is an efficient predator similar to temperate north American pike. It is very abundant but is primarily found in open waters with a moderate flow. Reproduction begins at the onset of the rainy season. It is considered harmless to humans. In the aquarium, the species does well in small school and might be sexually dimorphic (?). With the small samples obtained for OPEFE, the fish appears to scatters eggs and provides no parental care.

The documented pre-spawning behavior (furnished to Oregon State University, Neo-tropical Division) illustrates a male fish that approaches the female and swims a type of figure 8 pattern, up and around the female, while she holds immobile. This act is repeated several times. One can see the anal fins touch, but no evidence of sperm being released.

Due to mortality, no further examinations were conducted. In another situation; the egg scattering was observed at a pet store by a dealer who had kept two specimen's in captivity. While this information is vague, the fish provided no care to the released eggs. Both fish were approximately 12 cm SL. No larvae emerged from the spawn released (zygotes).

DESCRIPTION

Black blotch at the humeral region nearly round, not vertically elongate; 80-96 scales in the lateral line.

Distribution: Amazon and Orinoco River basins and rivers of north South America: Brazil, French Guiana, Guyana, Peru, Suriname and Venezuela.

Acestrorhynchus falcirostris (Cuvier, 1819) Opercle with dark patches, the upper separated from the lower by a very narrow pale stripe; 140-175 scales in the lateral line.

Acestrorhynchus grandoculis sp. n. (Menezes & Géry, 1983) 74-85 scales in the lateral line; 10-11 scale rows from the lateral line to origin of anal fin; eye very large, the orbital diameter about 31.0%-38.5% of head length. The species has very small, sometimes indistinct but strange dark blotch at the beginning of the lateral line behind the opercle. This marking helps distinguish it from A. microlepis (Schomburgk) and A. guianensis (Menezes) from the other remaining species of Acestrorhynchus. Fairly common species.

Acestrorhynchus heterolepis (Cope, 1878) Lateral line scales with two divergent branches of the laterosensory canal (Cope, 1878). Lateral line scales with only one branch of the laterosensory canal which is inclined either upward or downward. General color pattern consisting of one mildlateral dark stripe running from tip of snout to caudal base and another dark stripe extending from about end of maxillary to lower surface of caudal peduncle, inconspicuous anteriorly and wider above anal-fin base. A. heterolepis can be difficult to identify by morphology or even color. They have longitudinal stripes as juveniles and closely resemble isalinae. A helpful characteristic is the base of the tail where there is a red spot dorsally and a yellow spot ventrally. These spots and the stripes disappear as the fish exceeds 10 cm. At this point A. heterolepis develops the false nose and is thus very easy to confuse with A. falcirostris! These fish were trained to eat prepared as opposed to live food. (Tom Lorenz, 2007).

A. heterolepis - FEEDING SEQUENCE BY TOM LORENZ

Acestrorhynchus isalineae (Menezes & Géry, 1983) The body coloration pattern is similar to A. nasutus (Eigenmann). Two longitudal dark stripes run across the body (anterior/posterior). The superior stripe runs from the tip of the snout to the caudal base. The inferior one runs from the about the end of the maxillary to the lower part of the caudal peduncle, being rather diffuse anteriorly. This peculiar color pattern is not found in any of the previously known species of the genus Acestrorhynchus. The difference with this species and A. nasutus is that it has more scales on the lateral line (89-92 vs. 78-82), and more scales above (14-15 vs. 13-14) and below (9-10 vs. 8-9) the lateral line. It also has fewer anal-fin rays, more pectoral fin rays, more maxillary teeth, more teeth on the posterior part of the dentary. The head and the snout shorter, the body longer, eye smaller and the interorbital narrower.

Like A. nasutus it is a small species. Sexual dimorphism is seen on the males; the midlateral dark stripe is wider and more intense than in the female. The inferior stripe in the male is also more prominent and dark than the female. It is most unusual to see this type of color pattern-dimorphism in acestrorhynchin fishes. The species type-locality may be more broader than the samples examined so far. It may occur in other tributaries of the Rio Marmelos and the Madeira.

The species is named after Mrs. Isaline Drecq, wife of Mr. Guy van den Bossche, participant in the expedition which found the species. 84-92 scales in lateral line.

Acestrorhynchus lacustris (Lütken 1875) 89-102 scales in the lateral line; 23-26 scale rows from lateral line to origin of anal fin, 13-16 from lateral line to origin of anal fin.

Acestrorhynchus maculipinna sp. n. (Menezes & Géry, 1983) This species has the same two longitudinal dark stripes on the body that characterizes the color pattern of both A. nasutus and A. isalinae and set these 3 species apart from the remaining species of the genus. It differs from the other two species and all others by its very prominent large black spot on the dorsal fin.

Acestrorhynchus microlepis (Schomburgk, 1841) Considerable variation exists within specimens identified as A. falcatus and A. microlepis. Based on morphological and coloration differences associated with geographic distributions, we identified an undescribed form of A. falcatus from Casiquiare drainages (southern Venezuela), and another from the middle-lower Orinoco Basin.  The extensive morphological, meristic, and coloration variation observed in A. microlepis does not appear to be associated with geographic distribution, but further analysis is needed. Based solely on juvenile specimens.  (H. Lopez-Fernandez and K. O. Winemiller, Wildlife and Fisheries Sciences 2000 - 2001 Annual Report).108-122 scales in the lateral line; 20-22 scale rows from the lateral line to origin of dorsal fin, 15-18 from the lateral line to origin of anal fin. Syn. A. cachorro.

A. apurensis (Toledo-Piza & Menezes 1996) was described as an endemic within Venezuela’s western llanos Synonym of Acestrorhynchus microlepis (Schomburgk, 1841):  Acestrorhynchus apurensis (Toledo-Piza & Menezes, 1996). Diagnostic characters of A. apurensis grade into certain morphotypes of A. microlepis. It was concluded that A. apurensis is either a valid species with a broader distribution than previously believed, or is an invalid name based description of juvenile A. microlepis, a highly variable species.

Taxonomic problems remain even within the most intensively studied Neotropical taxa and regions. (H. Lopez-Fernandez and K. O. Winemiller, Wildlife and Fisheries Sciences 2000 - 2001 Annual Report).Synonym of Acestrorhynchus microlepis (Schomburgk, 1841):  Acestrorhynchus guianensis (Menezes, 1969).  93-106 scales in the lateral line; 17-19 scale rows from the lateral line to origin of dorsal fin, 13-15 from lateral line to origin of anal fin.

Acestrorhynchus minimus (Menézes, 1969) Black band absent on sides of body; a rather dark stripe from upper end of opercle to caudal base; anal fin rays v, 21-25; 74-86 scales in the lateral line; 12-14 scale rows from lateral line to origin of dorsal fin, 8-10 from lateral line to origin of anal fin.

Acestorhynchus nasutus (Eigenmann, 1912) (See A. isalineae above) General color pattern consisting of one midlateral dark stripe running from tip of snout to caudal base and another dark stripe extending  from about  end  of maxillary to lower surface of caudal peduncle, inconspicuous anteriorly and wider above anal-fin base. No distinct black spot on anterior basal part of dorsal fin. Considered rare. 78-82 scales in the lateral line.

Acestrorhynchus pantaneiro (Menezes, N. A. 1992) Grows to 24.0 cm SL. Commonly used as a bait fish (peixe-cachorrinho). Nuclear DNA content ranged from 1.70 ± 0.04 pg of DNA per diploid nucleus in Acestrorhynchus pantaneiro.

Morphological variation in Acestrorhycnus microlepis and A. falcatus (Characiformes: Acestrorhynchidae), reassessment of A. apurensis and distribution of Acestorhynchus in Venezuela.

Hernan Lopez-Fernandez and Kirk O. Winemiller - Ichthyol. Explor. Freshwaters, Vol. 14, No. 3, pp. 193-208, 4 figs. 5 tabs., October 2003.

Key to the species of Acestrorhynchus from Venezuela:

1.   -    Large humeral spot, generally shaped as an inverted teardrop, spanning from a third to almost the entire body height.
            ---------A. falcatus
      -     Humeral spot small or completely absent.
            ---------2

2.   -     Lateral line scales with bifurcated canals.
             --------- A. heterolepis
      -      Lateral line scales with simple canals
             ----------3

3.   -     Small dark spot behind the operculum.
             ----------4
      -     No spot behind the operculum.
            ----------5

4.   -     77-87 lateral line scales; eye 31.1-36.6%. HL; snout 26.3-33.3% HL.
            --------- A. grandoculis
      -     91-131 lateral line scales; eye 17.9-34.1% HL; snout 32.5-50.0% HL.
            ----------A. microlepis

5.   -     Dark, longitudal band extending from the tip of the snout through base of caudal fin. 
            ----------A. nasutus
      -     No longitudal band.
             ----------6

6.   -    Black pigmentation on edge of operculum, especially on dorsal half; 140-175 lateral line scales.
            ---------A. falcirostris
      -    Operculum unmarked; 74-85 lateral line scales.
            ---------A. minimus

ACKNOWLEDGEMENT

I take this opportunity to thank  Naercio Menezes for making his citations available in order to construct this web page. While most of the material is technical in nature, it still is helpful to those of you who are interested in the fish at a systematic level than just an aquarium pet. The key provided here are accurate to the citation and some notes mentioned are my own and not necessarily those of the author N. Menezes.

REFERENCES

• Géry, Jacques, Characoids of the World, TFH, 1977

• Menezes, N. A. 1969. Systematics and evolution of the tribe Acestrorhynchini (Pisces, Characidae). Arq. Zool. (Sao Paulo) 1-150

• Menezes, Naercio A., On the Cynopotaminae, a new subfamily of Characidae, Arq. Zool. S. Paulo, 28(2): 1-191, 1976.

• Menezes, Naercio A. and Géry, Jacques, Seven new Acestrorhychin Characid species (Osteoichthyes, Ostariophysi, Characiformes) with comments on the systematics of the group, Geneva, September 1983.

• Menezes, N. A. and Géry, J. 1983. Seven new acestrorhynchin characid species (Osteichthyes, Ostariophysi, Characiformes) with comments on the systematics of the group. Rev. Suisse Zool. 563-592

• Menezes, Naercio A., Three new species of the Characid genus Cynopotamus Valenciennes, 1849, with remarks on the remaining species (Pisces, Characiformes), April 1987.

• Taphorn, D., R. Royero, A. Machado-Allison and F. Mago Leccia, 1997. Lista actualizada de los peces de agua dulce de Venezuela. p.55-100. In E. La Marca (ed.) Catálogo zoológico de Venezuela. vol. 1. Vertebrados actuales y fosiles de Venezuela. Museo de Ciencia y Tecnologia de Mérida, Venezuela.

• Toledo-Piza, M. and Menezes, N. A. 1996. Taxonomic redefinition of the species of *Acestrorhynchus* of the *microlepis* group with the description of *Acestrorhynchus apurensis*, a new species from Venezuela (Ostariophysi: Characiformes: Characidae). Am. Mus. Novit. 1-23.

• Schomburgk, R. H. 1841. The Natural history of fishes of Guiana.--Part I. In: Jardine, W. (ed.), The Naturalists' Library. Vol. 3. W. H. Lizars, Edinburgh. [Also an 1852 edition, entitled the Fishes of British Guiana, as v. 39.] Fish British Guiana I [1-16], 17-263.

• Ferreira, E.J.G., J.A.S. Zuanon and G.M. dos Santos, 1998. Peixes comerciais do médio Amazonas.. Instituto Brasileiro do Meio Ambiente e dos Recursos Naturais Renováveis. 211p.

• Cuvier, G. 1819. Sur les poissons du sous-genre *Hydrocyon*, sur deux nouvelles espèces de *Chalceus*, sur trois nouvelles espèces du *Serrasalmes*, et sur l'*Argentina glossodonta* de Forskahl, qui est l'*Albula gonorhynchus* de Bloch. Mem. Mus. Natl. Hist. Nat. 351-379.

• Cope, E. D. 1878. Synopsis of the fishes of the Peruvian Amazon, obtained by Professor Orton during his expeditions of 1873 and 1877. Proc. Am. Philos. Soc. 673-701.

• Menezes, N. A. 1992. Redefinição taxonômica das espécies de *Acestrorhynchus* do grupo *lacustris* com a descrição de uma espécie (Osteichthyes, Characiformes, Characidae). Comun. Mus. Ciênc. PUCRS, Sér. Zool. Porto Alegre 39-54.

• Margarida Lima Carvalho, Claudio Oliveira, Maria Clara Navarrete, Otávio Froehlich and Fausto Foresti. Nuclear DNA content determination in Characiformes fish (Teleostei, Ostariophysi) from the Neotropical region. 
  Genet. Mol. Biol. v.25 n.1 São Paulo 2002.

• Hernan Lopez-Fernandez and Kirk O. Winemiller. Morphological variation in Acestrorhycnus microlepis and A. Falcatus (Characiformes: Acestrorhynchidae), reassessment of A. apurensis and distribution of Acestorhynchus in Venezuela. Ichthyol. Explor. Freshwaters, Vol. 14, No. 3, pp. 193-208, 4 figs. 5 tabs., October 2003.

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UPDATED: 12/27/2011