| Main Ref. | Tencatt, L.F.C. and H.-G. Evers, 2016 |
| Appearance refers to | |
| Bones in OsteoBase |
| Specialized organs | |
| Different appearance | |
| Different colors | |
| Remarks | Males possess an oblong pelvic fin (vs. rounded in females). |
| Striking features | |
| Body shape lateral (shape guide) | fusiform / normal |
| Cross section | |
| Dorsal head profile | |
| Type of eyes | |
| Type of mouth/snout | |
| Position of mouth | sub-terminal/inferior |
| Type of scales | |
| Diagnosis |
Corydoras knaacki is distinguished from its congeners by having the following combination of characters: a longitudinal black stripe along midline of flank; short mesethmoid, with anterior portion smaller than 50% of the bone length; serrations on posterior margin of pectoral spine directed towards the tip of the spine; dorsal fin with the region of the first branched ray, including membrane, with black pigmentation, the remaining areas with irregular black blotches; lacking a vertically elongated black blotch across the eyes; snout with conspicuously rounded moderately-developed black spots; and ventral expansion of infraorbital 1 moderately developed (Ref. 121196). |
| Ease of Identification |
| Lateral Lines | Interrupted: No |
| Scales on lateral line | |
| Pored lateral line scales | |
| Scales in lateral series | |
| Scale rows above lateral line | |
| Scale rows below lateral line | |
| Scales around caudal peduncle | |
| Barbels | |
| Gill clefts (sharks/rays only) | |
| Gill rakers | |
| on lower limb | |
| on upper limb | |
| total | |
| Vertebrae | |
| preanal | |
| total |
| Attributes | no striking attributes |
| Fins number | 1 |
| Finlets No. | Dorsal |
| Ventral | |
| Spines total | 2 - 2 |
| Soft-rays total | 7 - 8 |
| Adipose fin | present |
| Attributes | forked |
| Fins number | |
| Spines total | |
| Soft-rays total | 7 - 9 |
| Pectoral | Attributes more or less normal |
| Spines 1 | |
| Soft-rays 7 - 8 | |
| Pelvics | Attributes more or less normal |
| Position abdominal | |
| Spines | |
| Soft-rays 6 - 6 |