ABOUT Serrasalmus spilopleura COMPLEX FORMS

Is S. sanchezi a member?

In particular this singular Serrasalmus species cf spilopleura = S. sanchezi.

By Frank Magallanes


COMMON NAME:  Red throated Diamond Piranha, herein referred to Serrasalmus sanchezi.


Copyright. Do not use outside of OPEFE without permission. Educational Use Only.

S. spilopleura cf   Photo above by Dr. William T. Innes, listed as Serrasalmus spilopleura in Exotic Aquarium Fishes, The Innes Book, 20th Edition, 1979.





I wrote this article a few years ago while I was attempting to answer an ID question about Serrasalmus species cf spilopleura. A species loosely called SPILO CF (a trade name). I have made this page available as an historical document on how this species was eventually moved into a rhombeus-group member and not a spilopleura complex member. This species is probably or more than likely counterpart of S. irritans of Venezuela. A similar sized specimen. Now this species is properly placed as S. sanchezi of Peru locality only. Sufficient imports and examination have taken place and is now widely recognized as the proper name. I want to thank Brian Scott (TFH Publications) for his  help in rewriting this article so that it appears more coherent than its original form.


My Favorite Quote


Even as all kinds of men are needed to build up a community, even so we need all kinds of scientists to develop science in every possible direction. Some are very sharp and narrow-minded, others are broad-minded and superficial. Many scientists like Hannibal, know how to conquer, but not how to use their victories. Others are pedagogues. Others want to measure everything more accurately than it was before. This may lead them to the making of fundamental discoveries, or they may fail, and be looked upon as insufferable pedants...............George Sarton, in the Study of the History of Science.




S. spilopleura belongs to a complex of at least five closely related fishes. Of the five, two (S. medinai and S. neveriensis) are known from Venezuela while the remaining three are indigenous to more southern locations within Amazonas.


The species being discussed here is Serrasalmus sp. cf spilopleura or herein referred to by using a known common name (no scientific standing) of  Spilo CF. This fish is different from the typical S. spilopleura, which is often referred to by home aquarists as a ruby red spilo or gold spilo depending upon the geographical location of the specimen in question. Traits that are commonly used in the distinction of the name are based upon coloration and its presence of a sub-terminal band on the caudal fin. The dark-colored terminal band on caudal fin of the spilopleura CF touches the edge and is different from another, albeit closely related, species S. maculatus. Serrasalmus spilopleura resembles this species based on nearly all morphological features except for the snout when compared to S. maculatus.



The above specimen has been previously designated as a member of the S. spilopleura complex in published scientific literature.


This species have appeared in published piranha books and categorized as Serrasalmus spilopleura complex species in the past, there still remains an unanswered question as to what species this fish actually is. In the future, they may be completely excluded from the spilopleura complex and moved into another category, perhaps even the equally puzzling rhombeus complex. Several DNA (karylogical) studies have been recently completed on the spilopleura and rhombeus complex groups. However, the species in question here (to my knowledge) has not been examined closely as of today. Parasitological (otherwise known as Monogenoidea) studies are also being incorporated to help in narrowing down species distinctiveness. This too remains unknown by me.


Photo by Geoge Fear

Red Throat, Serrasalmus sp. cf spilopleura; Iguitos, Peru, Rio Itayi. Photos by George Fear


Definitions and Terms as used herein:

The term complex = a group of closely related species that have yet to be adequately described and distinguished. 

The term form = 1) a neutral term for a single individual, phenon, or taxon; a group, e.g. larvae and adult forms, male and female forms, ecological forms, and seasonal forms, 2) an infrasubspecific group, 3) in the past, a subspecies (not recommended usage). According to the International Code of Zoological Nomenclature the use of the term "form" before 1961 is not to be interpreted as an express statement of either subspecific or infrasubspecific rank and after 1960 it is to be regarded as of infrasubspecific rank.

Examples how  the term "complex, cf or cf  (= complex form)" is used in ichthyological citations:

Examples used in scientific collections where the term "complex" and "aff." is used:



Hobbyists will sometimes see a dealer’s inventory list with fishes listed as Serrasalmus sp. "Bolivia" or some other country listing. These are not scientifically accurate names rather they are acceptable common names that have little-to-no scientific value. These common names represent the dealer’s personal method in attaching a commercial or "trade" name to fishes that they don't know for sure what species the fish is. They may only know from where the specimens were collected. You should always take that locality data with "a grain of salt" however, unless you were there to collect it yourself because you cannot be one-hundred percent sure that the fish originated from the stated locality.


Photo used by permission of Dr. Peter Henderson, PISCES Conservation Ltd

photo by Matt Galich

Photo by Frank Magallanes

Photo by Frank Magallanes



The S. spilopleura CF also resemble somewhat the S. medinai a species presently known only from Venezuela. It remains to be determined if this is a geographical form of the Venezuela species or is distinctive as something else other than a spilopleura complex form. The problem with photographs it is not the same as having a specimen in front of you to make better evaluation using scientific methods. With this in mind; there are other differences from S. medinai and it is the snout. In medinai, the snout is short and blunt, in the Peru's specimen (based on the picture) the snout is rather long. Aside from possible internal skeletal differences, and the eye color (= yellow eyes for S. medinai). These two species look similar externally in color in my opinion.


Photo by Frank Magallanes

S. spilopleura CF Photo by Frank Magallanes

Photo by Daniel Caballero

S. medinai from Venezuela. Photo by Daniel Caballero



AND S. maculatus GUAPORE?


Photo by Frank Magallanes

S. spilopleura CF, photo by Frank Magallanes

Photo by George Fear

S. spilopleura, note the hyaline edge, photo by G. Fear

Photo courtesy of Dr. Michel Jegu

Compare to S. maculatus, photo courtesy of Michel Jégu



Another similar appearing species is S. maculatus (KNER 1858). With that species, the subterminal band forms a dark edge to the caudal fin. S. spilopleura always have a clear broad edge to the caudal fin. With S. spilopleura there is always present a humeral spot. S. maculatus does not have one. S. spilopleura CF differs somewhat from these other 2 forms.


WHAT ABOUT S. sanchezi PERU?


To  my knowledge this species has not been presently compared with S. medinai or other species, however, I believe this question will be presented and answered by scientists, as more explorations of other piranha species continue throughout South America. One other species to consider is S. sanchezi. A fish described from Peru only. While updating OPEFE web pages on species, I had the opportunity to re-read and translate much of the French text from the original citation pertaining to S. sanchezi. I encourage everyone who has not an opportunity, to go visit S. sanchezi page.




As seen from the fishes above, these fish also look similar to another juvenile form called Pygocentrus nattereri, the red-bellied piranha. But with some very marked differences externally. These fish are often seen mixed in with displayed Pygocentrus nattereri and it is not unusual finding them mixed in Public Aquariums lurking among the pack of these freshwater killers which they resemble by coloration and spotting. In the wild, these fish are also collected alongside P. nattereri. They are considered harmless wherever they occur.


This complex form generally have well developed serrae on the belly and coloration is very reddish-orange fiery on the breast which gives its distinctive hobbyists name of; diamond or red-throated piranha. Some of these imports are often mistakenly identified as a species of S. rhombeus. The head is narrow, the eye large with a small black band transecting the eye. The eye is reddish-orange. The check is (opercle) has a blemish. A diffused but fixed humeral spot is present behind the opercle. Their body scales shimmer with brilliance almost metallic in texture. The body has large spots numerous, smaller in size to the iris of the eye, spotting is obscured by the bright metallic silvery scales, as is the anal fin is tinted reddish to reddish-orange fading posteriorly to hyaline to the end. A thin, darkish black marginal band distally from the anal fin. The caudal fin at the base is darkish black with a lighter stripe in the middle and the terminal band is black. Their body is very compressed, high backed, yet thicker anteriorly than those of the compressus group. The occasional adults, the jaw teeth extend outward over the lips, very exposed, almost oversized in appearance. 


The pectoral fins are lightly tinted with orange, the ventral fins are hyaline. The adipose fin is grayish-black with a thin black margin distally. Juvenile fish between 20 mm to 55mm SL strongly resemble S. rhombeus, but are only slightly distinctive. In older juveniles the appearance of blood red coloration of the throat then becomes distinctive. The form of the body is much more laterally compressed and less elongated than S. rhombeus of similar size.  For that reason they are difficult to discern from rhombeus when grouped together as juveniles.

S. spilopleura has been seen in various piranha books under the name S. gibbus or even as Serrasalmus calmoni but this species referred as S. spilopleura CF looks nothing like these fish. David Schleser in his PIRANHAS A Complete Pet Owner's Manual, has several photographs and a bit of information on S. spilopleura CF.  




The species is very shy preferring to hide behind a rock or floating plant roots. Sometimes, the fish can be seen in the aquarium calmly approaching a victim, act as if it not going to bother it all. Sometimes, it just ignores the victim for a period of time. Then suddenly bite at that fishes fins. This type of stealth attack and feeding is a renewable resource of food for this piranha, since the fins are full of protein and grow back quickly. They are colorful and not uncommon to find them with bright red throats and diamond-like speckles on the body that shimmer in the light. The fish grows to about 17.8-20 cm SL (David Schleser, 1997).




 This species appears limited to the Upper Amazon basin in Peru.




Temperature requirement in the aquarium is; 23 - 28°C; pH range: 5.0 - 7.0; dH range: 18.0. 




Dissertação de Mestrado aprovada pela PUCRS em 2001 com o título:  Aspectos da biologia da piranha Serrasalmus spilopleura (Characidae) no Município de Uruguaiana, oeste do Estado do Rio Grande do Sul, Brasil. Rodrigo C. and P. Beheregaray Porto Alegre - RS - Brasil.

Froese, R. and D. Pauly. Editors. 2002. FishBase.
World Wide Web electronic publication. 13 November 2002.

Cavicchioli, M; Nakatani, K; Shibatta, OA (1997): Morphometric variation of larvae and juveniles of the piranhas Serrasalmus spilopleura and S. marginatus (Characidae: Serrasalminae) of the Paraná basin, Brazil. Ichthyol. Explor. Freshwaters 8 (2), 97-106.

Fink, W.L. 1993 Revision of the piranha genus «Pygocentrus» (Teleostei, Characiformes). Copeia 1993(3):665-687

Spix, J.B. von & Agassiz, L. 1829 Selecta genera et species piscium quos in itinere per Brasiliam annos MDCCCXVII-MDCCCXX jussu et auspiciis Maximiliani Josephi I... collegit et pingendos curavit Dr. J.B. de Spix... Monachii. This is a book. Part 1:i-xvi+i-ii+1-82, pl.1-49; Part 2:83-138, pl.49-101.

Schleser, David M. 1997, Piranhas, A Complete Pet Owner's Manual, Barron's Educational Series, This is a book. pg. 60, 66, 78-80.








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