Brachyplatystoma Filamentosum

''Brachyplatystoma filamentosum'', commonly called ''piraíba'', ''kumakuma'', ''valentón'' or ''lau lau'', is a species of catfish of the family Pimelodidae that is native to Amazon and Orinoco River basins and rivers in the Guianas and northeastern Brazil. It is an important predator in its ecosystem, and in turn is a food fish.

Description

The name "''piraíba''" is used by locals to define B. filamentosum specimens larger than 1.6 m (50kg), while the term "''filhote''" is used for smaller individuals.

The piraíba reaches up to in length and in weight, though most individuals of ''B. filamentosum'' don't reach these dimensions, more commonly being . Juveniles exhibit dark body spots or blotches.

'' B. capapretum'' was recognized as distinct from ''B. filamentosum'' and described in 2005. These two species are very closely related, being sister genera. They can be differentiated through premaxillary dentition, juvenile and adult coloration, and adult maxillary barbel length and caudal fin shape. Both species exhibit spotting in their juvenile stages, though in ''B. filamentosum'' these spots are about the same size as the eye, while in ''B. capapretum'' these spots are much larger in size. The adult ''B. capapretum'' has a very dark or even black dorsum (its species name is derived from Portuguese which means ''black cape''), as opposed to the relatively lighter dorsal surface of ''B. filamentosum''.

Adults have dark gray coloration on the dorsal side of the body, with a lighter white underside. They have paired pectoral fins, pelvic fins, a single unpaired dorsal fin, anal fin, and an adipose fin. The caudal fin is forked. While their body structure is somewhat reminiscent of a shark, they can be identified by their 3 pairs of barbels around the mouth.

The mitogenome of the piraíba was sequenced in 2025; it was found to possess 16,566 base pairs.

Distribution

The species is found in rivers and estuaries of Amazon and Orinoco watersheds, Guianas and northeastern Brazil.

Ecology

''Brachyplatystoma filamentosum'' is found in both freshwater and brackish water systems. The species is a demersal potamodromous fish that commonly inhabits deeper, flowing channels with soft bottoms.

The piraíba is strongly predatory, mainly preying on a wide variety of fish. The fish preyed upon include '' Achirus'' soles; characins from the genera ''Brycon'', ''Colossoma'', ''Hemiodus'', ''Leporinus'', ''Myleus'', ''Mylossoma'', '' Prochilodus'', ''Schizodon'', '' Semaprochilodus'', ''Rhytiodus'', ''Triportheus'', along with indeterminate Curimatidae; catfish such as '' Ageneiosus'', ''Calophysus'' vulture catfish, ''Hypophthalmus'', ''Pareiodon'' candiru, ''Pimelodella'', ''Pimelodus'', ''Sorubim'', and indeterminate members of the families Cetopsidae, Pimelodidae, and Trichomycteridae; Cichlids, Gymnotiformes, ''Pellona'', and drums like '' Pachypops'' and '' Plagioscion''. The piraíba is notable for tackling difficult prey items, such as toxic '' Colomesus'' pufferfish and stingrays; armored catfish among the Doradidae and Loricariidae, such as ''Doras'' and ''Oxydoras''; and other predatory fish like ''Pseudoplatystoma'' and '' Rhaphiodon'' are all taken by the piraíba, solidifying its position as top-order carnivore. Only the river dolphins has been recounted to prey on the piraíba, but even then, they may fail at killing and consuming much of the catfish; the doomed piraíba is then left crippled and at the mercy of the currents and riverine scavengers, such as the two genera of catfish referred to as candiru, and the aptly-named vulture catfish.

Piraíba begin their life as ichthyoplankton, metamorphosing through their larval stages as they drift downriver The young take aquatic invertebrates, such as diplostracans, rotifers, and aquatic insects, along with other arthropods adrift in the current. Eventually, they reach the estuary, where they remain for some time to continue growing and maturing. Eventually, the immature fish swim up the river to return to their spawning grounds. Mature adults may then return to the estuary to feed.

Spawning tends to occur in rising and high water periods, typically between February and June. In their larval stage, their diet consists mostly of insect remains and plankton, similar to other fish that are piscivorous as adults. Piraiba migrate across the amazon basin throughout their life. They rear their young in both upstream and estuarine environments.

Relation to humans

Piraíba are considered to be game fish, but are more valuable as a food fish; it was considered to be the 6th most important species fished in the Brazilian Amazon in 1998. Due to overfishing, catches have been declining.

These large species are used as food for people in South America, specifically the communities that are housed around the rivers. The skin residue is high in fatty acids and proteins, and is a usable alternative for several products, including gelatin. Gelatin is primarily produced using cows, which may introduce the risk of bovine spongiform encephalopathy. Fish residue as an alternative would mitigate this risk, as well as the other consequences of using cattle products.

Piraiba have often been said to be man-eaters, with claims of attacks or human remains having been reported. As recounted in the book ''Through the Brazilian Wilderness'', during the Roosevelt–Rondon Scientific Expedition, Theodore Roosevelt and company claimed to have consumed a -long catfish of an unspecified species that contained the mostly digested remains of a monkey, which "astounded" the American expeditioners. Brazillian members of the expedition though shared stories of the piraiba; "a grayish-white fish over nine feet long, with the usual disproportionately large head and gaping mouth, with a circle of small teeth"; the expedition's doctor had witnessed two men killing a piraiba using their machetes after the fish had apparently jumped towards their canoe "with open mouth", with the fish's carcass subsequently paraded around town. Colonel Rondon said that the people inhabiting the lower Madeira constructed "stockaded enclosures in the water in which they bathed", ostensibly to protect from both the piraiba and the "big cayman"; the catfish were as or even more feared than the "big cayman" by swimmers, as the piraiba's habit of ambushing from the "bottom of the water" supposedly made it more dangerous than the caimans, which were more visible in comparison.

Furthermore, in one account documented on the television series ''River Monsters'', a local fisherman was apparently found having been swallowed head-first up to his waist by a piraíba, with neither the fish nor the fisherman surviving the encounter. However, the episode itself states that the details surrounding this account are vague and unreliable.

Piraíba are sometimes kept in aquaria, although the adults need a very large tank to accommodate their swimming.

Conservation status

Piraiba, along with other large amazon catfish species, are important apex predators in the Amazon Basin. This water body serves as a central source for fisheries in South America, providing food for communities in the area.

However, this species, along with several other South American catfishes, are declining in population. Local fisheries are struggling due to overfishing, with records of decreasing catches being a primary indicator of their decline. These catfish are migratory, meaning they are especially sensitive to dam construction and habitat degradation, which impede their ability to migrate throughout the waterways.

Piraiba, along with other predator fish, are also susceptible to mercury contamination; this, along with their role as an important food source, puts many local communities at risk.

Fisheries there are poorly studied and we know relatively little about these species, so our understanding of the ecological impacts are also limited. Chemical analysis of otoliths within specimens has proven to help researchers study migratory patterns of Piraiba, helping provide evidence of their life stages at different regions. This serves as an alternative method to physically monitoring their behavior, which eliminates several difficulties the latter method raises.

References

{{Taxonbar, from=Q1577680

Brachyplatystoma
Fish of the Amazon basin
Fish of Bolivia
Catfish of Brazil
Freshwater fish of Colombia
Freshwater fish of Ecuador
Fish of French Guiana
Fish of Guyana
Freshwater fish of Peru
Fish of Suriname
Freshwater fish of Venezuela
Taxa named by Hinrich Lichtenstein
Fish described in 1819