As mentioned, one of the characteristics of this genus is caudal fin filaments on younger fish. In most of the species these filaments are lost in adulthood, though they are retained in "B. tigrinum", "B. juruense", and "B. platynemum". Many "Brachyplatystoma" exhibit countershading, in which the dorsal surface is darker, and then fades to a lighter belly. In most species, this is consistent throughout life, though there are some exceptions. Juvenile "B. capapretum" and "B. filamentosum" exhibit dorsal and lateral spots which mostly disappear in the adult form. Juvenile "B. juruense" and "B. tigrinum" exhibit lateral spots that expand to form vertical stripes as the fish matures.