B. capapretum, described in 2005, was previously confused with
B. filamentosum. These two species are very closely related, being
sister genera. They can be differentiated in
premaxillary dentition, juvenile and adult coloration, and adult maxillary barbel length and caudal fin shape. Both species exhibit spotted juvenile stages, though in
B. capapretum these spots are much larger than the eye, while in
B. filamentosum these spots are about the same size as the eye. Also, the
cross section of the
caudal peduncle is rounded in these two species, as opposed to a deeper, thinner cross section in other
Brachyplatystoma species. 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.
B. capapretum grows to a length of at least and a weight of ==Distribution==