| Main Ref. | Whitehead, P.J.P., 1985 |
| Appearance refers to | |
| Bones in OsteoBase |
| Specialized organs | no special organs |
| Different appearance | males alike females |
| Different colors | males alike females |
| Remarks |
| Striking features | none |
| Body shape lateral | fusiform / normal |
| Cross section | compressed |
| Dorsal head profile | clearly concave |
| Type of eyes | more or less normal |
| Type of mouth/snout | more or less normal |
| Position of mouth | superior |
| Type of scales | cycloid scales |
| Diagnosis |
Body elongate, with strongly convex lower profile bearing a sharp keel of 33 to 38 scutes. Lower jaw prominent, mouth pointing obliquely upward; upper jaw short, not reaching beyond eye center. Anal fin very long, its origin well before midpoint of body. A dark spot behind gill opening. |
| Ease of Identification |
| Lateral Lines | Interrupted: No |
| Scales on lateral line | 0 - 0 |
| Pored lateral line scales | |
| Scales in lateral series | |
| Scale rows above lateral line | 0 - 0 |
| Scale rows below lateral line | 0 - 0 |
| Scales around caudal peduncle | |
| Barbels | 0 |
| Gill clefts (sharks/rays only) | |
| Gill rakers | |
| on lower limb | 23 - 27 |
| on upper limb | |
| total | |
| Vertebrae | |
| preanal | |
| total |
| Attributes | greatly reduced or absent |
| Fins number | 1 |
| Finlets No. | Dorsal 0 - 0 |
| Ventral 0 - 0 | |
| Spines total | 0 - 0 |
| Soft-rays total | |
| Adipose fin | absent |
| Attributes | forked; more or less normal |
| Fins number | 1 |
| Spines total | 0 - 0 |
| Soft-rays total | 81 - 93 |
| Pectoral | Attributes more or less normal |
| Spines 0 | |
| Soft-rays | |
| Pelvics | Attributes suppressed/absent |
| Position absent | |
| Spines 0 | |
| Soft-rays 0 - 0 |