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| Pseudoplatystoma | |
|---|---|
 | |
| Pseudoplatystoma tigrinum | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Siluriformes |
| Family: | Pimelodidae |
| Genus: | Pseudoplatystoma Bleeker, 1862 |
| Type species | |
| Silurus fasciatus Linnaeus, 1766 | |
| Synonyms | |
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Pseudoplatystoma is agenus of severalSouth Americancatfish species of thefamilyPimelodidae. The species are known by a number of differentcommon names. They typically inhabit major rivers where they prefer themain channels and tend to stay at maximum depth, but some species can also be seen in lakes,flooded forests, and other freshwater habitats. They have robust bodies and are importantfood fish. Recently, their populations have been on the drastic decline due to a variety of factors, includingoverfishing andhabitat destruction due to the construction ofhydroelectric dams.
Pseudoplatystoma is amonophyletic genus of catfishes.[1]P. fasciatum was the first species to be described, under the nameSiluris fasciatus.[2] In 1829,P. corruscans was described under the namePlatystoma corruscans, and over a decade later,P. tigrinum was described asPlatystoma tigrinum.[3] In 1862,Pseudoplatystoma was described and these species transferred to it, withP. fasciatum astype species.[4]
Unrecognized species ofPseudoplatystoma have been included under the namesP. fasciatum andP. tigrinum for decades. This genus traditionally contained only three species until 2007; currently, eight species are in this genus.P. orinocoense,P. magdaleniatum, andP. reticulatum were formerly recognized asP. fasciatum, but are now recognized as distinct species.P. metaense is also now recognized as a distinct species fromP. tigrinum.[1]
Twoclades are recognized within the genus. One is theP. fasciatum clade which includesP. fasciatum,P. orinocoense,P. magdaleniatum,P. reticulatum, andP. corruscans. Within this clade,P. fasciatum andP. punctifer aresister species, andP. orinocoense is sister to the clade formed by these two species. The other, theP. tigrinum clade, includes onlyP. tigrinum andP. metaense. They are differentiated by anatomical characters.[1]
The intergeneric relationships of this genus are well established. It forms amonophyletic group withSorubim,Sorubimichthys,Hemisorubim, andZungaro. Of these genera,Hemisorubim is most closely related toPseudoplatystoma.[5]
In their native waters, these fish may be calledsurubí inGuaraní, especially in Paraguay, where still both Spanish and Guaraní are spoken. This name is also used in someSpanish-speaking countries and inPortuguese-speakingBrazil (surubi orsurubim). InPeruvian Spanish, they are calleddoncella orzúngaro.P. corruscans may be calledmoleque orpintado.[6] They often are referred to in the vernacular asbagre rayado/rajado orpintadillo/pintado (tiger catfish or tiger–shovelnose).[1]P. corruscans,P. fasciatum, andP. tigrinum are also known asspotted sorubim,barred sorubim, andtiger sorubim, respectively.[3][2][7] This genus is collectively referred to as thetiger shovelnose catfish in theaquarium hobby, as the species in this genus are relatively easy to confuse.
Pseudoplatystoma species are all large and boldly striped or spotted catfishes. They are familiar due to their distinctively marked color patterns. They are also recognized due to a depressed head, anoccipitalprocess extending backward to contact the predorsal plate, and a very longfontanel.[1]
Aftergonadal maturation, females tend to grow faster than males.[6] They have a large, depressed head with an expandable mouth. The eyes and teeth are small. They have dorsal and pectoral fin spines;P. fasciatum also has an additional, smaller, dorsal spinelet preceding the dorsal spine.[5] They exhibit typicalbarbels of catfish, the maxillary barbels sometimes being quite long, especially in juveniles.
The currently recognized species in this genus include:[1][8]
JuvenilePseudoplatystoma fish are quite different in appearance from adults, distinct in patterning and coloration; the juvenile is dark on its back with an obvious boundary between the white of its sides and belly; also, the stripes ofP. fasciatum andP. tigrinum have not developed, being present as spots. The adult color is brown-olive, with about 13 or 14 dark transverse bands reaching up to the belly, which is white with a few dark spots.[9]
The distribution ofPseudoplatystoma species includes the great river basins of South America: theAmazon,Orinoco,Paraná,São Francisco,Magdalena,Rupununi,Essequibo, andSuriname Rivers. They can also be found in the Cuiabá river, located in the Brazilian State of Mato Grosso.They have not been reported from river basins draining into thePacific.[1]P. fasciatum inhabits the Guyana region, including the Essequibo and Suriname Rivers and their tributaries, inGuyana,Suriname, andFrench Guiana.P. tigrinum is found in the Amazon River inBrazil,Colombia,Ecuador,Peru, andVenezuela.P. corruscans originates from the Paraná and São Francisco Rivers inArgentina, Brazil,Paraguay, andUruguay.P. orinocoense is named for and endemic to the Orinoco River of Venezuela.P. metaense is distributed in the Orinoco River in Colombia and Venezuela; it is named for theMeta River, thetype locality, a tributary of the Orinoco River.P. magdaleniatum is named for and endemic to the Magdalena River drainage, including theCauca River of Colombia.P. reticulatum inhabits the central Amazon and Paraná Rivers in Argentina, Bolivia, Brazil, Paraguay, and Uruguay.[1]
Pseudoplatystoma species live in a diverse range of habitats, such as great rivers, lakes, side channels, floating meadows, and flooded forests.[1]P. fasciatum is found in river beds and sometimes in flooded forests. Though it is biologically similar toP. tigrinum, this fish seems to favor shadier streams.[2]P. tigrinum occurs inestuarine zones, mainly upstream of the first rapids up to the basin's headwaters. They live in the main bed of slow or fast zones, and the juveniles particularly live in flooded forests.[7]
These fish arenocturnal hunters, primarilypiscivorous, feeding on fish such aselectric knifefishes,cichlids, armoredloricariid catfish, andcharacins such assábalos, andbogas.[3][2] Being opportunistic feeders, they may also feed oncrustaceans such ascrabs orshrimp.[7]
Pseudoplatystoma species are allmigratory fish.[5]P. orinocense andP. tigrinum make short migrations.[1] At the end of the dry season,P. tigrinum can migrate at the same time as its prey, and then return at the end of the rainy season.[7]
The migration ofP. corruscans is heavily tied to flooding. The greatest reproductive activity, the highest rate of development ofgonads, and the most energy spent in migration happens when rainfall occurs.[6]
Pseudoplatystoma species are of considerable economic value; all are sold in fish markets throughout South America.[1] They are important food fish for human consumption.[6]P. fasciatum has a succulent, yellowish flesh without "stray" bones.[2]P. tigrinum is the most important catfish in gill-net fisheries ofGuaporé andMarmoré Rivers.[7] These fish are beingoverexploited in their range, and uncontrolled fishing possibly has led to the disappearance ofPseudoplatystoma species in some local tributaries of the Amazon, Orinoco, and Magdalena.[5] In the Argentine province ofEntre Ríos alone, about 27,000tonnes ofPseudoplatystoma species are harvested every year, comprising 70 to 80% of the total capture there, mostly concentrated on the fishing area near the city ofVictoria, oppositeRosario,Santa Fe.[citation needed]
The capture ofP. corruscans has declined greatly due to changes in their environment. This fish has a high commercial value due to the excellent quality of its flesh, its high marketability, and its marked participation in commercial fishing. Spawning of this fish can be induced withhormones, with a high potential for commercial production.[6]
P. fasciatum andP. tigrinum are often found in public aquaria.[2][7]
JuvenilePseudoplatystoma fish are marked as ornamental fish in both North and South America, but they are usually at a size too small for certain identification, but more than one species may be imported.[1] These species appear in theaquarium hobby, where they are most often sold under the name "tiger shovelnose" or "tiger shovelnose catfish". These fish prove to be hardy, but their large adult size is problematic for both matters of housing and finding suitable tankmates that will not be consumed. With the appetite these fish have, finding enough good food may present some difficulty.[10]