Brachyhypopomus alberti is distinguished from other species of the genus Brachyhypopomus by the following combination of characters: absence of depigmented stripe along middorsal region of body (vs. prominent pale uninterrupted middorsal stripe from occipital region to base of caudal filament in B. arrayae, B. beebei, B. belindae, B. gauderio, B. pinnicaudatus, and B. verdii); 20-22 precaudal vertebrae (vs. 15-19 in B. batesi, B. benjamini, B. bennetti, B. bombilla, B. bullocki, B. cunia, B. diazi, B. hendersoni, B. menezesi, B. provenzanoi, B. regani, and B. sullivani); anal fin with 182-202 rays (vs. 226-293 in B. brevirostris); presence of continuous or discontinuous dark vertical or diagonally oriented bands or saddles on body surface dorsal to lateral line, often extending across lateral line into ventral lateral surface (vs. absence of oblique bands or saddles on body surface dorsal to lateral line in B. draco, B. flavipomus, B. jureiae, and B. palenque); 3 bilateral columns of electrocytes at the anal-fin terminus (vs. 4-5 in B. janeiroensis and B. occidentalis (except some populations in Colombia and Venezuela); absence of dark suborbital stripe (vs. presence in B. walteri). It differs from most but not all specimens of B. hamiltoni by having a higher number of pectoral-fin rays 15-16 (mode 16) (vs. 12-15 (mode 13) (only 2 of 18 measured specimens of B. hamiltoni exhibited an overlapping number of pectoral-fin rays with B. alberti). It can be differentiated from B. hamiltoni by the absence of the first of five branchiostegal rays (vs. presence in B. hamiltoni Mago-Leccia) (Ref. 116763).