From Boulenger (1909, pp. 107-108)
Depth of body 3 1/4 to 4 1/3 times in total length, length of head 4½ to 5 times. Head not or but slightly longer than deep, with feebly curved, declivous upper profile; snout 2/7 to 1/3 length of head; teeth conical or truncate, 5 or 7 in upper jaw, 6 in lower; a globular mental appendage, as long as eye or a little shorter; eye about 2/3 length of snout, 2/3 to ¾ interorbital width. Dorsal 28-32, originating above 7th to 13th ray of anal, 1/2 to 2/3 its distance from head. Anal 35-40, nearer base of caudal than base of ventral. Pectoral pointed, nearly as long as head, about twice as long as ventral, extending beyond base of latter. Caudal covered with scales, with long pointed lobes. Caudal peduncle 3 to 3½ times as long as deep, as long as head or a little shorter. 70-85 scales in lateral line, 14-18 / 20-22 in transverse series on body, 13-16 / 12-15 in transverse series between dorsal and anal, 12 round caudal peduncle. Brown, or brown above and silvery below. Type from Stanley Falls (Kisangani, D.R. Congo)
Easily confused with Marcusenius monteiri with which it frequently co-occurs. Coloration of these two species are quite similar and head shape only subtly different. M. stanleyanus has conical teeth, while those of M. monteiri are bicuspid. Most noticeable on upper teeth. EOD waveforms are also diagnostic.
EOD waveforms of Marcusenius stanleyanus are approximately 0.25-0.35 milliseconds in duration and have three to four phases. The first phase is a head-negative pre-pulse closely followed by a head positive and then a head-negative phase. In some, there is a noticeable head-positive "overshoot" fourth phase.
to 400 mm SL
Congo River Basin. See Fishbase for museum records and localities.
Occurs in larger rivers.