Brachyplatystoma filamentosum
Piraíba
Classification
Order: Siluriformes Family: Pimelodidae
Distribution
Widely-distributed throughout most of the Amazon and Orinoco river drainages plus other important fluvial systems in the Guianas and northeastern Brazil. The type locality is given simply as ‘Brazil’.
Habitat
Found in a number of habitat-types, though rarely in smaller tributaries, generally preferring deeper, flowing channels through which it travels for considerable distances at certain times of year. Like other large, migratory pimelodids these movements are typically associated with nutrient-rich, white water drainages rather than nutrient-poor black waters.
When the Amazon begins to rise at the start of the wet season, freshwater is pushed into its delta and the normally brackish waters recede, allowing juveniles and sexually-immature adults of several migratory catfish species, including B. filamentosum, to enter the area and feed on polychaetes, bivalves, crustaceans, and other fishes.
This rich feeding ground is exploited until the sea water returns, at which point the catfishes begin to migrate upstream in massive numbers, moving up the Amazon and its tributaries. Sexually mature individuals are not normally recorded during these events so they’re thought related to feeding and dispersal rather than spawning.
The fish are subject to intensive capture by commercial and artisanal fishing operations during this upstream movement.
Spawning occurs in often-distant headwaters and the fry are washed downstream to the delta, a process estimated to take 13-20 days in the congener B. rousseauxii. Juveniles then remain in the estuary region for around three years, entering the delta to feed when conditions permit. They then move into the lower and middle Amazon where they may remain for a further year as they continue to feed and grow.
Following this period of growth schools of adults begin to form and make their way into headwaters in order to spawn. There is no single spawning ground for a given species, rather there appear to exist distinct populations in different watersheds, and there exists evidence to suggest that individuals may return to the particular tributary in which they were born to spawn.
Study of B. rousseauxii has revealed that sexually mature adults are found only in the western Amazon, with no mature individual ever recorded east of Manaus despite the intensive commercial fishery operating there.
The total distance covered by some populations during migration from the delta was as much as 5500 km, making it the longest known in any freshwater fish species. Sexually-mature adults of B. flamentosum have been observed in the upper rio Araguaia basin, some 2000 km from the estuary.
Maximum Standard Length
The largest catfish of the Amazon basin with adults typically measuring 2000 – 2500 mm (2 – 2.5 m) and weighing in excess of 150 kg.
Aquarium SizeTop ↑
This species is suitable only for public aquaria plus a very small minority of private aquarists and as such we offer no recommended aquarium size.
Maintenance
The choice of décor is as much down to personal preference as anything else though a carefully-aquascaped, planted set-up is obviously out of the question.
A sandy substrate with some large chunks of driftwood, or a completely bare arrangement are perhaps the most-favoured options in privately-owned aquaria, but provided water quality is maintained and lighting not too bright this species is relatively unfussy. An enormous, reliable filter system and rigorous maintenance regime should be considered mandatory.
Water Conditions
Temperature: 22 – 28 °C
pH: 6.0 – 8.0
Hardness: 18 – 357 ppm
Diet
Almost entirely piscivorous preying on loricariids and other bottom-dwelling fishes in nature but most specimens readily adapt to dead alternatives such as prawn/shrimp, mussel, squid, whitebait, strips of larger white fish, etc., in aquaria. Adults require just a single meal per week at most.
Behaviour and CompatibilityTop ↑
Only keep with species large enough to avoid predation.
Sexual Dimorphism
Unknown.
Reproduction
Unrecorded in captivity, perhaps unsurprising given its complex natural life cycle (see ‘habitat’).
NotesTop ↑
In the Amazon region it is only specimens larger than around 160 cm and werighing in excess of 50 kg that are referred to as ‘Piraíba’ with the name ‘filhote’ normally applied to smaller individuals. Other vernacular names include ‘Salton catfish’, ‘Kumakuma’ and ‘tiger antenna catfish’ with members of the genus often referred to collectively as ‘goliath catfishes’.
Externally it can be told apart from the very similar-looking congener B. capapretum by its larger adult size (maximum SL recorded for B. capapretum is 880 mm), longer maxillary barbels (extending beyond base of adipose fin, vs. never extending beyond base of adipose fin), deeply-forked caudal fin with upper lobe usually longer than the lower (vs. moderately-forked with lobes of equal size) and body colouration in adults dark dorsally, countershading gradually along the flanks into the paler ventral shade (vs. very dark dorsal colouration countershading abruptly along flanks).
It’s distinguished from all other congeners by the following external characters: colour pattern in adults strongly but gradually countershaded along flanks; dorsum dark to light grey; often small dark spots on caudal-fin or peduncle; colour pattern in juveniles comprising small dark spots on and above lateral line; caudal-fin in adults deeply-forked with broad lobes of which the upper is usually longer; eye diameter fits approximately 5-7 times in length of snout; maxillary barbels in adults extending beyond base of adipose-fin, sometimes base of caudal-fin; caudal peduncle compressed with greater depth than width; origins of adipose and anal fins approximately in line; base length of adipose and anal fins approximately equal; adipose-fin approximately height approximately twice its length; opercle subquadrangular; 15-17 anal-fin rays.
These two species are the only members of the genus in which juveniles exhibit dark body spots or blotches both on and above the lateral line, these being relatively smaller in B. filamentosum than B. capapretum.
Brachyplatystoma spp. are distinguished from all other catfishes by two synapomorphies. The first comprises several morphological characters relating to the skull, specifically that the mandibular suspensorium (that which connects the lower jaw bone to the skull) is greatly expanded mediodorsally to form a large plate approaching the parasphenoid bone, with the hyomandibula and metapterygoid similarly enlarged.
The second is the presence of an elongate filament formed from a single, unbranched simple ray on both caudal fin lobes in juveniles and subadults. These become shorter or are lost in adult specimens of B. vaillantii, B. filamentosum, B. rousseauxii, and B. capapretum but retained in B. juruense, B. platynemum and B. tigrinum.
References
- Batista, J. S. and J. A. Alves-Gomes, 2006 - Genetics and Molecular Research 5(4): 723-740
Phylogeography of Brachyplatystoma rousseauxii (Siluriformes - Pimelodidae) in the Amazon Basin offers preliminary evidence for the first case of “homing” for an Amazonian migratory catfish. - Ferraris, C. J., Jr., 2007 - Zootaxa 1418: 1-628
Checklist of catfishes, recent and fossil (Osteichthyes: Siluriformes), and catalogue of siluriform primary types. - Lundberg, J. G. and A. Akama, 2005 - Copeia 2005(3): 492-516
Brachyplatystoma capapretum: a new species of goliath catfish from the Amazon basin, with a reclassification of allied catfishes. - M. Petrere Jr., R. B. Barthem, E. A. Córdoba and B. Corrales Gómez, 2004 - Reviews in Fish Biology and Fisheries 14: 403-414
Review of the large catfish fisheries in the upper Amazon and the stock depletion of piraíba (Brachyplatystoma filamentosum Lichtenstein).
