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Subfamily Serrasalminae or Family Serrasalmidae?

Keeping up with the scientific changes

By Frank Magallanes, OPEFE

Photo (left) demonstrates different body forms of the pirambeba S. rhombeus (top)and the piranha P. nattereri  (bottom)














Genera of





From Frank Magallanes


Photo by Frank MagallanesThe systemic of the Characiformes has long been (and continues to be) a difficult task to undertake. They were recognized as a homogeneous group in 1844 by German ichthyologist's Müller and Trochel. The Viennese Kner and his student Steindachner (between 1858-1915) followed by describing accurately a number of species without paying much attention to the classification. It was not until much later that Carl H. Eigenmann (considered to be the Father of Characoidologist) established the natural classifications of characins from South America. His principal manuscripts were posted between 1910 and 1927. He was then followed by one of his students Dr. George S. Myers. Within recent modern times a series of anatomical studies was completed by S. Weitzman, T. Roberts, William L. Fink, Antonio Machado-Allison and many others helped establish the critical position of several groups, which led to the recognition of many families within the suborder (a recognition that would not have been accepted during Eigenmann's time). The research revealed the importance, as well as the complexity, of the Characiformes, and is presently considered as a key-group among teleosts. Included in this huge grouping to be discussed specifically at this website are the Serrasalmin which includes the pacus, silver dollars, pirambebas and of course, the true piranhas. The first authoritative division of the Characoids into several families (16) was done by S. Weitzman, in Greenwood et al. (1966). The French ichthyologist J. Géry (1972) would modify this order in a later manuscript.


Piranha and Pirambeba have distinctive body differences which become apparent as maturity sets in. These differences are the key reason why South American natives call non-true piranhas by other names. It is only outside South America (or S. A. non-fishing city dweller's) that the name "piranha" is loosely applied to all species within the subfamily Serrasalminae.













The name Serrasalminae means saw-salmon-family the saw or serration pertaining to the scutes (or serrated keel) found on the belly of these fishes. Both carnivorous (single row teeth per jaw) and the vegetarian (double row teeth per jaw) practice mimicry. Perhaps this has much to do with the ecological home they inhabit and survival.


The epithet piranha is perhaps the most over used common name on fishes that could not even be scientifically called piranhas. It has been used for Serrasalminae vegetarian fishes and other related forms. In order to properly understand what a piranha is, one must do some research into common names and how they are applied. The Piranha Book, edited by Dr. G. S. Myers, (pg 26, TFH Publications Inc.,1972) covers what the usage of common names should be defined as. I recommend the research student use that reference to understand common name usage.


I frequently use the loose term piranha when I am discussing the "carnivorous" group as a whole, since this is the name more closely associated with the fish. For specifics, I prefer the Brazilian pirambeba for the species not genus Pygocentrus. For the true piranhas placed in genus Pygocentrus I use the epithet Caribe or Piranha. Caribe pertains to the Spanish Venezuelan piranhas but is a much more loose application since many of the piranha-like forms are also called that. But if you get a native fishermen and try to pin him down he will simply distinguish the more innocuous species with another name or the true caribe as caribe. The same holds true for epithet piranha. The native fishermen will give another name for the piranha-like and use the name piranha for the most dangerous ones in genus Pygocentrus. One last thing, native fishermen do not use scientific names in describing their fishes, we do! So we must be careful when attaching a common name to a scientifically described fish.


It has been common practice for biologists, news media and laymen to describe vegetarian fishes (pacus and tambaqui) in the genera Colossoma or Piaractus as belonging to the "piranha family" they are not! Pacus, and piranhas are all members of the Characidae family that hosts well-over 2,000 species of fish. The Characidae family (loosely called tetras) are delineated into groups or subfamilies.


There have been several unsuccessful attempts to split the sub-family into 2 groups; Mylinae (pacus and such) and the Serrasalminae (piranhas and associated forms) during the course of ichthyologic history. Norman (1929) lumped the both groups into one subfamily naming it Serrasalmoninae, but got the spelling wrong (should have been Serrasalminae.) His basis was certain characters found on both species. But the problem was much deeper than simple character assimilation. It was the advent of Phylogenetic and DNA evidence which now prevents such delineation. DnA research has also been used to separate the species with results proving confounding. Some species merged to the surprise of experts. A good case is the species Catoprion mento  (the wimple piranha), this species is closest (sister) to Pygocentrus in genetic terms. Ichthyologists over the centuries have kept this particular species separate in its own ranking, but with genetics it puts it closer to the true piranhas. The wimple piranha is a good example of a species having the surname "piranha" while it is NOT a real piranha by definition (see Myers, 1972).


Most recently, genus Metynnis was discovered to be closely aligned with genus Pygocentrus using Phylogenetic and DNA sequencing.


Other species like P. denticulata, which is a piranha, have unique, specialized teeth which help it remove seed husks, much like a pacu's teeth.





Family Serrasalmidae Classification: Dr. Jacques Géry; The French ichthyologist Jacques Géry (1972), modified the group into a new family and sub-family adding a sub-genera which further delineated the piranhas, pirambebas, and the vegetarian silver dollars and pacus;


  • Class: Osteichthyes

  • Superorder: Teleostei

  • Order: Cypriniformes

  • Suborder: Characoidei

  • Family: Serrasalmidae

  • Sub-family: Serrasalminae

  • genus Serrasalmus

  • sub-genus Pristobrycon

  • sub-genus Pygopristis

  • sub-genus Pygocentrus

  • sub-genus Serrasalmus

  • sub-genus Taddyella

  • Sub-family: Catoprioninae

  • genus Catoprion

  • Sub-family: Mylinae

  • genus Colossoma

  • genus Mylossoma

  • genus Myleus

  • sub-genus Myloplus

  • sub-genus Paramyloplus

  • sub-genus Prosomyleus

  • sub-genus Myleus

  • genus Uiaritichthys

  • genus Metynnis

  • genus Acnodon

  • genus Mylesinus


Géry split the group based on several factor's listed below

  1. Teeth variable, usually in more than one row on upper jaw (exceptions occur in Serrasalmidae). Anal fin moderate or long, with at least 3 unbranched rays and 10 branched ones (with a few exceptions in certain regressed species).

  2. Scales usually cycloid (with some exceptions) with circuli of caudal (apical) zone parallel or even divergent with axis of body (except Serrasalmidae).

  3. Maxilla reduced, not toothed; dorsal fin long, with at least 16 rays; usually a predorsal spine and a series of ventral spines (serrae) (body very compressed, usually disciform; teeth variable according to diet; scales small, the circuli concentric).



  • Kingdom: Animalia

  • Phylum: Chordata

  • Subphylum: Vertebrata

  • Superclass: Osteichthyes

  • Class: Actinopterygii

  • Subclass: Neopterygii

  • Infraclass: Teleostei

  • Superorder: Ostariophysi

  • Order: Characiformes

  • Family: Characidae

  • Subfamily: Serrasalminae


Subfamily Serrasalminae Classification - Dr. William L. Fink & Dr. Antonio Machado-Allison


The most recent evaluation of the number of species, valid names, alimentary habits and their Phylogenetic relationship with other groups was investigated by Fink and Machado-Allison (Fink, 1978; Machado-Allison, 1982a, 1985). Their present findings do not substantiate the further splitting as revised by Géry (1972). The reasoning behind this is because Phylogeny is the now the standard norm. The basic issue is that many of the older classifications, accepted non-monophyletic groups as valid to be named. There is evidence that some "pacus" are more closely related to piranhas than other "pacus" ie; that some pacus share a more recent common ancestor with piranhas than with the other pacus. That makes the group "pacus" non-monophyletic (actually paraphyletic). In relation to today's modern Phylogenetic classifications, the older methods of determining classification (or ranking) is outdated. The older classifications were not built with the Phylogenetic philosophy in mind. Right now the evidence on pacu/piranha relationships is equivocal and its doesn't seem to be useful to revise the previous classifications.


The ranks are entirely arbitrary--there is no scientific basis for any ranking procedure, so accepting a group as a subfamily or family is entirely a matter of taste. See below for further arguments.







Phylogeny of the Serrasalminae (Characiformes) based on mitochondrial DNA sequences

Previous work (Ortí et al. 1995) based on DNA sequences of mitochondrial (mt) rRNA genes showed three main groups within the subfamily Serrasalminae:


(1) a basal clade of herbivores (Colossoma, Mylossoma, Piaractus);

(2) the "Myleus" clade (Myleus, Mylesinus, Tometes);

(3) the "piranha" clade (Serrasalmus, Pygocentrus, Pygopristis, Pristobrycon, Catoprion, Metynnis). The genus Acnodon was placed as the sister taxon of clade (1+2). However, poor resolution within each clade was obtained due to low levels of variation among rRNA sequences.


Complete sequences of the hypervariable mtDNA D-loop are now presented for a total of 40 taxa representing all genera in the subfamily to address intragroup relationships. Phylogenetic analyses of these sequences identify the same groupings as before and provide further evidence to support the following observations:


(a) the genera Serrasalmus and Pristobrycon are paraphyletic and form a group that also includes Pygocentrus;

(b) Catoprion, Pygopristis, and Pristobrycon striolatus form a well supported clade, sister to the group described above in 'a';

(c) distinction of subgenera within Myleus (i.e., Myleus, Prosomyleus, Myloplus) is not supported;

(d) Mylesinus and Myleus are paraphyletic, since Tometes sp. is the sister taxon of Mylesinus paraschomburgkii and Mylesinus paucisquamatus is most closely related to other species of Myleus.

Present taxonomic structure as accepted by the U.S. systematists et al. (note the different and much shorter structure from the Géry classification above): The Tree of Life which is Phylogenetic based is controversial in many ways. It establishes a new order of animals that would not have been accepted by previous 19th and early 20th century authors.


The levels at the generic (binomen) are not subdivided into lower ranking than genus. That is the main difference with the Géry classification method which does not use Phylogenetic methods in placing his fishes and the fact he uses subgeneric ranking.


This cladogram places several vegetarian fishes into the "piranha" clade. Unthinkable during Eigenmann's time.





Animation source:



Phylogeny of the Serrasalmidae (Characiformes) based on mitochondrial DNA sequences

Guillermo Ortí, Arjun Sivasundar1, Kelly Dietz and Michel Jégu2


School of Biological Sciences, University of Nebraska, Lincoln, NE, USA. Genetics and Molecular Biology, 31, 1 (suppl), 343-351 (2008) Copyright © 2008, Sociedade Brasileira de Genética. Printed in Brazil





Previous studies based on DNA sequences of mitochondrial (mt) rRNA genes showed three main groups within the subfamily Serrasalminae: (1) a “pacu” clade of herbivores (Colossoma, Mylossoma, Piaractus); (2) the “Myleus” clade (Myleus, Mylesinus, Tometes, Ossubtus); and (3) the “piranha” clade (Serrasalmus, Pygocentrus, Pygopristis, Pristobrycon, Catoprion, Metynnis). The genus Acnodon was placed as the sister taxon of clade (2+3). However, poor resolution within each clade was obtained due to low levels of variation among rRNA gene sequences. Complete sequences of the hypervariable mtDNA control region for a total of 45 taxa, and additional sequences of 12S and 16S rRNA from a total of 74 taxa representing all genera in the family are now presented to address intragroup relationships. Control region sequences of several serrasalmid species exhibit tandem repeats of short motifs (12 to 3 bp) in the 3’ end of this region, accounting for substantial length variation. Bayesian inference and maximum parsimony analyses of these sequences identify the same groupings as before and provide further evidence to support the following observations: (a) Serrasalmus gouldingi and species of Pristobrycon (non-striolatus) form a monophyletic group that is the sister group to other species of Serrasalmus and Pygocentrus; (b) Catoprion, Pygopristis, and Pristobrycon striolatus form a well supported clade, sister to the group described above; (c) some taxa assigned to the genus Myloplus (M. asterias, M tiete, M ternetzi, and M rubripinnis) form a well supported group whereas other Myloplus species remain with uncertain affinities (d) Mylesinus, Tometes and Myleus setiger form a monophyletic group.


Key words: piranhas, pacus, D-loop, phylogeny, Bayesian inference. Received: September 13, 2006; Accepted: April 19, 2007.


Taken from: Phylogeny of the Serrasalmidae (Characiformes) based on mitochondrial DNA sequences Guillermo Ortí, Arjun Sivasundar, Kelly Dietz and Michel Jégu, School of Biological Sciences, University of Nebraska, Lincoln, NE, USA.):


Piranhas and pacus (Serrasalmids) form a distinctive assemblage of characiform fishes. For a long time, they were considered a subfamily within the family Characidae. Recent phylogenetic studies of these fishes, however, strongly suggest that Characidae is non-monophyletic and that serrasalmids are not closely related to taxa originally placed in the subfamily Characinae, or other characid subfamilies (Zanata, 2000), but rather that they may be more closely related to Anostomoidea (Calcagnotto et al., 2005).


All these arguments support the separate family status of piranhas and pacus; their relationships to other families within the order Characiformes, however, remain uncertain (Ortí and Meyer, 1997; Calcagnotto et al., 2005; Hubert et al., 2005). Species of the Serrasalmidae are endemic to the Neotropics and are distributed widely in all the major river systems of South America. At least 60 species (in 15 genera) have been recognized. This family includes the well known piranhas, notorious from accounts of their group predatory behavior, the seed-eating tambaquí, which is highly regarded as a food species, and the pacus. Several serrasalmid species are of economic importance and are used in aquaculture (Junk, 1984; Marshall, 1995; Araujo-Lima and Goulding, 1997) . Although based on a single molecular marker (mtDNA), the results of this study carry several taxonomic implications. Most notably, many of the generic designations in the family seem to lack support or are clearly contradicted by the data. Some of these conclusions are not new: Pristobrycon striolatus has previously been regarded as quite distinct from its congeners (Machado-Allison et al., 1989), differing in several morphological aspects and its well-supported grouping with Catoprion and Pygopristis is consistent with the finding of Ortí et al. (1996)(Ortí, Sivasundar, Dietz and Michel Jégu 2008).


Our present results confirm this observation and therefore we prefer to restrict Pristobrycon to the single species P. striolatus, and place all other taxa previously assigned to this genus in Serrasalmus.


According to the classification of Géry (1977), the genus Serrasalmus contained the subgenera Pygopristis, Pristobrycon, Pygocentrus, Taddyella and the nominate subgenus Serrasalmus; Serrasalmus (Pristobrycon) striolatus was noted to resemble closely the subgenus Pygopristis. This observation is well supported by our molecular analysis of control region data, as this species forms a clade with Catoprion and Pygopristis (Figure 4), and is not closely related to the other specimen putatively assigned to Pristobrycon (#224 designated Serrasalmus serrulatus here) in the rRNA tree (Figure 2).


Based on various morphological characters, Serrasalmus gouldingi is distinct from other members of the genus (Machado-Allison and Fink, 1996). In this analysis, it was found to be more closely related to the remaining Pristobrycon than it is to other species of Serrasalmus. This group containing S. gouldingi, S. eigenmanni and S. serrulatus is the sister group to the Serrasalmus- Pygocentrus clade. The genus Serrasalmus contains within it the genus Pygocentrus.




Family Serrasalmidae


Genus Pygocentrus

Species: piraya, nattereri and cariba

Genus Serrasalmus

Species: All other taxa here

Genus Pristobrycon

Species: striolatus, gouldingi(?), eigenmanni(?) and serrulatus(?)

Genus Catoprion

Species: mento

Genus Metynnis

Species: Taxa under consideration


Results from analysis of control region sequences of a dense taxonomic sampling for Serrasalmus and Pygocentrus provides strong evidence for the monophyly of Pygocentrus but its relationship to diverse components of Serrasalmus remains unresolved (Hubert et al., 2007). Some of the poor resolution obtained in our study is evidently the consequence of poor taxonomic sampling  (Ortí, Sivasundar, Dietz and Michel Jégu 2008).


Some authors (e.g. Géry, 1977) have recognized the existence of four subgenera within Myleus, namely Myloplus, Paramyloplus, Prosomyleus and the nominate subgenus Myleus, within this genus. These subgeneric distinctions have been, as with all previous classifications, based primarily on dental morphology. Other authors, however, rejected these subgeneric distinctions due to the lack of autapomoprhies (Machado-Allison and Fink, 1995). The monophyly of subgenera within Myleus is not supported by analyses of mtDNA data. Analysis of the Myleus group reveals the polyphyly of the formerly designated genus Myleus and supports the taxonomic rearrangement proposed by Jégu and Dos Santos (2002) and Jégu et al. (2003), but relationships among the various components of this group remain tentative. The group formed by Myleus setiger with Mylesinus and Tometes is relatively well-supported (PP = 1.00, BV = 67, Figure 3) suggesting strong affinities of Myleus with species designated to these genera. A robust group of Myloplus species (M. rubripinnis, M. asterias, M. tiete, and M. ternetzi) is also well supported by the control region data. As these analyses have shown, there are several taxonomic inconsistencies in this subfamily. While this study represents the most comprehensive molecular systematic treatment of this group, and utilizes a highly variable mtDNA marker to provide resolution of shallow nodes, placement of some taxa remains uncertain. In order to provide a strong foundation for taxonomic revision of the group, future studies would benefit from utilizing dense taxonomic sampling, nuclear gene sequences, together with mtDNA and morphological characters (Ortí, Sivasundar, Dietz and Michel Jégu 2008). To read more about these new revisions contact the authors above or read the .pdf VIEW


Isolation by distance and Pleistocene expansion of the lowland populations of the white piranha Serrasalmus rhombeus




*†§ *U.R. 175 Institut de Recherche pour le Développement (IRD), GAMET, BP 5095, 361 rue JF Breton, 34196 Montpellier Cedex 05, France, † Instituto de Biología Moleculary Biotecnología, Universidad Mayor de San Andres, La Paz, Bolivia, ‡Unidad de Limnologia y Recursos Aquaticos, Universidad Mayor de San Simon, Cochabamba, Bolivia, § Laboratoire Génome, Populations, Interactions, Adaptation, CNRS-IFREMER-Université Montpellier II, UMR 5171, SMEL, 1 Quai de la Daurade, 34200 Sète, France





The genetic variability and distribution of Amazonian fish species have likely been influenced by major disturbance events in recent geological times. Alternatively, the great diversity of aquatic habitat in the Amazon is likely to shape ongoing gene flow and genetic diversity. In this context, complex patterns of genetic structure originating from a joint influence of historical and contemporary gene flow are to be expected. We explored the relative influence of Pleistocene climatic fluctuations and current water chemistry on the genetic structure of a piranha, Serrasalmus rhombeus, in the Upper Amazon by the simultaneous analysis of intron length polymorphism and mitochondrial DNA sequences. The Madeira river is well suited for that purpose as it is characterized by a great diversity of water types, the presence of one of the largest floodplain of the Amazon and the potential occurrence of two Pleistocene refuges. We found evidence of genetic structure even at a small geographical scale (less than 10 km), indicating that the floodplain is not a homogenizing factor promoting interdrainage dispersal in S. rhombeus. Likewise, the hierarchical genetic structure inferred was correlated to geographical distance instead of habitat characteristic. Our results also support the hypothesis that the area underwent population expansion during the last 800 000 years. In addition, a higher level of genetic diversity was found in the samples from the putative Aripuanã refuge. The present findings suggest that Pleistocene refuges contributed significantly to the colonization of the lowlands in the Upper Amazon valley during the Pleistocene.


Keywords: Characidae, museum hypothesis, Neotropics, nonequilibrium, population expansion, refuge hypothesis

Received 6 November 2006; revision received 20 February 2007; accepted 5 March 2007


To read more about these revisions contact the authoris above or read the .pdf VIEW


Phylogeography of the piranha genera Serrasalmus and Pygocentrus: implications for the diversification of the Neotropical ichthyofauna




Institut de Recherche pour le Développement (IRD), U.R. 175 CAVIAR, 361 rue JF Breton, BP 5095, 34033 Montpellier Cedex 1, France, Département Milieux et peuplements aquatiques, Unité Biodiversité et dynamique des communautés aquatiques, US MNHN 0403, Muséum National d’Histoire Naturelle, 43 Rue Cuvier, 75231 Paris Cedex 05, France, Institut de Recherche pour le Développement (IRD), U.R. 131 Biodiversité des grands Cours d’Eau, 213 rue La Fayette, 75480 Paris Cedex 10, France, Instituto de Investigaciones de la Amazonía Peruana, Programa de Ecosistemas Acuáticos, Iquitos, Perú, Instituto de Biología Molecular Biotecnología, Universidad Mayor de San Andrés, La Paz, Bolivia, **Unidad de Limnología y Recursos Acuatícos, Universidad Mayor de San Simón, Cochabamba, Bolivia





The phylogenetic relationships within the piranhas were assessed using mitochondrial sequences with the aim of testing several hypotheses proposed to explain the origin of Neotropical diversity (palaeogeography, hydrogeology and museum hypotheses). Sequences of the ribosomal 16S gene (510 bp) and control region (980 bp) were obtained from 15 localities throughout the main South American rivers for 21 of the 28 extant piranha species. The results indicate that the genus Serrasalmus is monophyletic and comprises three major clades.The phylogeographical analyses of these clades allowed the identification of five vicariant events, extensive dispersal and four lineage duplications suggesting the occurrence of sympatric speciation. Biogeographical patterns are consistent with the prediction made by the museum hypothesis that lineages from the Precambrian shields are older than those from the lowlands of the Amazon. The vicariant events inferred here match the distribution of the palaeoarches and several postdispersal speciation events are identified, thereby matching the predictions of the palaeogeography and hydrogeology hypotheses, respectively. Molecular clock calibration of the control region sequences indicates that the main lineages differentiated from their most recent common ancestor at 9 million years ago in the proto Amazon-Orinoco and the present rate of diversification is the highest reported to date for large carnivorous Characiformes. The present results emphasize that an interaction among geology, sea-level changes, and hydrography created opportunities for cladogenesis in the piranhas at different temporal and geographical scales.


Keywords: Amazon, biogeography, Brooks parsimony analysis, molecular clock, mtDNA, phylogeny, piranha

Received 3 August 2006; revision received 20 November 2006; accepted 11 December 2006


To read more about these revisions contact the authors above or read the .pdf VIEW


J Mol Evol. 2003 Apr;56(4):464-72.

Mitochondrial genomics of ostariophysan fishes: perspectives on phylogeny and biogeography.


Saitoh K, Miya M, Inoue JG, Ishiguro NB, Nishida M.

Source Tohoku National Fisheries Research Institute, Shinhama, Shiogama 985-0001, Japan.




Ostariophysi is the second largest superorder within Teleostei. It contains five orders: Gonorynchiformes, Cypriniformes, Characiformes, Siluriformes, and Gymnotiformes. Resolving the higher-level relationships among ostariophysan and related fishes will aid in resolving basal teleostean divergence and provide basis to historical biogeographic analysis of major freshwater fish groups. In this study, we report the complete mitochondrial (mt) DNA sequences for eleven ostariophysan fishes and the results of phylogenetic analyses including these species plus four other ostariophysan and nine non-ostariophysan teleostean fishes. Maximum likelihood and maximum parsimony analyses reconfirmed clupeiforms as the closest relatives of ostariophysans. However, gonorynchiforms were closer to clupeiforms than to otophysans (ostariophysan groups excluding gonorynchiforms), thus raising a question over the current definition of Ostariophysi. The lack of clarity in otocephalan (ostariophysans + clupeiforms) basal relationships implies that such divergence took place over a short period of time. The monophyly of cypriniforms, characiphysans (characiforms, siluriforms, and gymnotiforms), and orders or superorders outside the ostariophysans examined here were conceivably reconstructed. The phylogenetic hypothesis suggests a Pangean origin of otophysans. Within characiphysans, gymnotiforms and siluriforms have independent evolutionary origins and evolutionary histories comparable to or older than that of characiforms. This helps to explain the present geographic distribution of characiphysans















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