Brachyplatystoma capapretum

Type locality is 'Rio Tefé sand beach, Lago Mucura, Supiã-Pucu, Tefé' in Amazonas state, northwestern Brazil, but this species is widely-distributed throughout much of the Amazon basin from Belém near the river's mouth at least as far as Iquitos in Loreto region, northern Peru.

It also occurs in most major Amazon tributaries including the Trombetas, Madeira, Purus, Negro, Manacapuru, Purus, Tefé, Putumayo, Juruá, Jutaí, and Içá.

Mostly inhabits larger, deeper river channels.

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.

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.

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.

Only keep with species large enough to avoid predation.

Unknown.

Has never been bred in captivity. In nature the congeners B. vaillantii and B. rousseauxii are known to undertake extensive, seasonal, upstream migrations which relate directly to the reproductive cycle but B. filamentosum appears not to do so (Petrere Jr. et al., 2004).

This species can be told apart from the very similar-looking congener B. filamentosum by its smaller adult size (B. filamentosum can grow to almost 3 m in length), shorter maxillary barbels (never extending beyond base of adipose fin (vs. extending beyond base of adipose fin), moderately-forked with lobes of equal size (vs. deeply-forked caudal fin with upper lobe usually longer than the lower) and body colouration in adults very dark dorsally with countershading abruptly along flanks (vs. dark dorsally, countershading gradually along the flanks into the paler ventral shade).

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 larger in B. capapretum than B. filamentosum.

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.