Diagnosis: Marcusenius krameri can be distinguished from its congeners by following characters: middle body depth 21.9-28.1% of standard length; distance from dorsal fin origin to end of caudal peduncle 39.9-41.7% of standard length; distance from anal fin origin to end of caudal peduncle 42.8-44.9% of standard length; dorsal fin length 15.5-20.0% of standard length; anal fin length 23.2-25.5% of standard length; depth of caudal peduncle 26.0-40.6% of its length; scales around caudal peduncle 16; total vertebrae 44; anterior gill rakers (5-6)+(5); total anterior gill rakers 10-11; posterior gill rakers (8)+(9); total posterior gill rakers 17; dorsal fin rays 22-25; anal fin rays 28-31; scales along lateral line 69-72; conical teeth on upper/lower jaws 4-6 (Ref. 95448).
Description: Head with terminal mouth well in front of eye; mental lobe on lower jaw protruding in front of upper jaw; head and body compressed; snout rounded and blunt; pre-anal distance shorter than pre-dorsal distance; distance from origin of anal fin to origin of dorsal fin slightly greater or equal to middle body depth; pre-pelvic distance twice as long as the distance between pelvic and anal fins (Ref. 95448). Dorsal and anal fins set well back on the body, situated about two thirds of standard length from the snout and opposite each other; dorsal fin shorter, originating on vertical at 4th or 5th anal-fin ray and ending before anal-fin base; distal margin of dorsal and anal fins obliquely orientated, with rays becoming gradually shorter posteriorly; dorsal fin rays 22-25, its anterior rays highest; anal fin rays 28-31; anterior anal fin rays of sexually mature males strong and sometimes darker, 3rd-5th rays longer than first two rays, crescentic and rounded or curved backwards, but anteriorly sharp or pointy in females and juveniles; pectoral fin rays 10, fin length 53.7-82.3% of head length (Ref. 95448). Body depth 21.9-28.1% of standard length; caudal peduncle slender, subcylindrical across its entire length, 17.6-24.5% of standard length; caudal peduncle depth 26.0-40.6% of its length (Ref. 95448). Lateral line scales 69-72, cycloid and with reticulate striae; 16 scales around the caudal peduncle (Ref. 95448). Jaws with 4-6 conical teeth; 44 vertebrae; gill rakers on anterior side more developed, total anterior gill rakers 10-11 on the first gill arch, gill raker of anterior side conicals with thin tips; total posterior gill rakers 17 on the posterior side of first gill arch; gill rakers on posterior side shorter, thicker and with flattened tips (Ref. 95448).
Colouration: Immediately after death specimens are medium brown, speckled with darker, irregular blotches on the sides, fins yellowish; in 70% alcojol, the head, fins and upper back sometimes covered by milky-grey mucus layer (Ref. 95448).