FROM FRANK MAGALLANES

Recommend keeping as solitary species in home aquarium. The species is an ambush predator and does not use stealth to bite its prey. This torpedo shaped piranha is the only elongated species of its kind. They are notorious fin biters and should be kept alone in the aquarium. There is some concern about this fishes "elongated form." Depending on the locality this fish may appear more rhomboid than elongated. Historically, it was supposed to be sexually dimorphic based on an anal fin blemish. I have not had the opportunity to investigate this species completely as specimens are rarely imported for the aquarium trade. Those that are imported command high prices from the pet trade.

INTRODUCTION

The species is not very prolific and very little is known about the habits during the first stages of the development, nonetheless, the few obtained the data demonstrate it to be principally a predator from early age consuming fins and scales of other fish. The adults are found in deep, white water of the main channels. The juveniles are frequently found in black and white waters and are generally associated with lagoons of floating aquatic plants. The breeding of this species has not been accomplished by hobbyists. The species is very rare and its actual requirements are not known. However, there is some material (compiled here) that may be of some use to hobbyists wishing to try breeding this species. Light requirements (moderate) would probably be the same as those found in Llanos of Venezuela. Orinoco rivers: pH: 4.5-7 (6.0); 2-8 dH (6); 75-82°F (24-28°C). Because this species has never been bred in captivity, it is my recommendation that a 200 gallon or larger tank be used. Also suggest heavy planting (back and sides) of the tank with a gravel and sand mixed tank be used. Filtration should be heavy on one side (power head) and moderate on the other (wet/dry system recommended). I base my recommendation on the "bigger" tank theory because it remains unknown what the minimum tank size would be for this species which is more rhombeus-like in its habits. S. rhombeus is found in open rivers and this fish is too. Water changes, while important is not as important as keeping the water stable and within the parameters suggested above. These torpedo-shaped fishes need fast current, yet requirements for breeding are like those of other piranhas. S. elongatus lives in the flooded forest where they are frequently found. As an adult they are generally found in large rivers or found in huge permanent lagoons. The area also undergoes a period of a dry season from October - March. The rainy season runs from April - September.

Characiformes usually are visually-oriented diurnal fishes with large eyes; they dwell in well-lit surface waters (Lowe-McConnell 1975, Fink & Fink 1979, Moyle & Cech 1996). In contrast, catfishes are primarily nocturnal and have sensory adaptations (e.g. tactile and chemical receptors) to low visibility (Hara 1971, Lowe-McConnell 1975, Fink & Fink 1979). Another problem with these types of fish is that they are fin biters and you may lose some specimens (due to predation) before anything significant happens in your aquarium. Like the vast majority of piranhas, the breeding process can be very bloody and pieces of flesh or fins will be part of the process. But in the end  you will have accomplished a most rare occurrence for the home aquarium.

SCIENCE

Historically, the species was placed as a member of the humeralis group (Géry, 1976), known then as S. pingke. The group consisted of; S. gibbus [see inset left] (Castelnau, 1855), S. humeralis (Eigenmann, 1915) and S. pingke (Fernández-Yépez, 1951). Morph-metrically these species appear similar. Member of these clade had included; S. humeralis (synonym S. iridopsis, COPE, 1871), S. eigenmanni (Norman, 1929), S. elongatus (Kner, 1860) and S. nalseni (Fernández-Yépez, 1951). Mago-Leccia (1990) placed S. pingke as a distinct species from S. elongatus in genus Serrasalmus from Venezuela.  Machado-Allison and Fink (1996) examined plenty examples of Serrasalmus pingke including juvenile forms (54.0 and 58.0 mm SL). The morphometric counts and other characters are very incomplete. Serrasalmus elongatus was compared with S. rhombeus and they are different in coloration, anal fin rays, number of spines and other characters, including a large pre-dorsal spine. Some juveniles of S. irritans are elongated at the early stages of life, but even so, they are not as elongated as S. elongatus and this is placed as the valid species name. Michel Jégu compared S. gibbus with S. elongatus and while both species appeared similar in certain characters, Jégu placed S. gibbus as a distinct species separate from S. elongatus. New morph types of S. rhombeus are being discovered that may very well exclude S. gibbus as a valid species name. S. rhombeus is a very complex species that is appearing in different body shapes, including elongated forms but not as elongated as S. elongatus, which remains a valid distinctive species.

S. pingke was originally described from Río Apure, La Defensa, suroeste de San Fernando de Apure, Estado Apure, Venezuela. Later authors put it in Brazil and other regions because of the confusion with S. elongatus.

S. elongatus was described from Rio Guapore, Mato Grosso, Brazil. But is now considered widespread in Bolivia, Brazil, Ecuador, Peru and Venezuela.

COLOR OF LIFE

Juveniles are generally silvery-green on the body without distinctive spots or marks with an exception being a dark blemish found the caudal of some specimens. The fins are hyaline and transparent. In adults the body is generally bright silvery in the dorsal-lateral and posterior of the body. The pectoral and pelvic fins are orange to fiery red. A black blemish (the diameter of the eye) is found in the humeral region near the first few scales of the lateral line. The head is dark dorsally; silver with yellow and orange coloration on the regions of the ventral-lateral and mandible. The orbit (eye) is red. The dorsal and anal fin are gray. The anal fin has a dark band distally from the first primary rays. The caudal and adipose fin are very dark in adults of large size. Small specimens have the adipose fin more hyaline. The pectoral and pelvic fins are colored red to orange tinting. (Machado-Allison and Fink, 1996).

LOCALITY

Amazon and Orinoco River basins

• Rio Guaraiquito, Laguna La Yuca, GU

• Rio Apure, Caño Los Zorros, Boquerones, AP

• Rio Chimire, Paso Chimire, GU

• Rio San José, GU

• Rio Apure, Viejo, AP

• Caño El Rodeo, 100 K. E. Est Gas, AP

• Hato Santa Rosa, Esteros de Camaguán, GU

• Carretera Guayabal, GU

• Lag. La Raya, Cano Falcón, GU

• Rio Apure, Las Guanotas, AP

• Laugun Terecaya, Soledad, AN

• Caño Falcon, La Raya, Camaguán, GU

• Rio San José, El Polvero, GU

• Caño Guaraguapo. afl, Rio Orinoco, DA

MAXIMUM SIZE

REFERENCES

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UPDATED: 07/10/2009