| Main Ref. | Collette, B.B., 1999 |
| Appearance refers to | |
| Bones in OsteoBase |
| Specialized organs | |
| Different appearance | |
| Different colors | |
| Remarks |
| Striking features | striking type of mouth |
| Body shape lateral | eel-like |
| Cross section | circular |
| Dorsal head profile | more or less straight |
| Type of eyes | more or less normal |
| Type of mouth/snout | other (see diagnosis) |
| Position of mouth | terminal |
| Type of scales | |
| Diagnosis |
Gill rakers present; dorsal fin rays few, 12-15; caudal peduncle greatly depressed with very large keel on each side (Ref. 9682). See also Ref. 1602. |
| 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 | 0 |
| Gill clefts (sharks/rays only) | |
| Gill rakers | |
| on lower limb | 6 - 7 |
| on upper limb | 4 - 5 |
| total | 10 - 12 |
| Vertebrae | |
| preanal | |
| total | 62 - 75 |
| Attributes | no striking attributes |
| Fins number | 1 |
| Finlets No. | Dorsal 0 - 0 |
| Ventral 0 - 0 | |
| Spines total | 0 - 0 |
| Soft-rays total | 12 - 15 |
| Adipose fin | absent |
| Attributes | forked; asymmetric |
| Fins number | 1 |
| Spines total | 0 - 0 |
| Soft-rays total | 15 - 20 |
| Pectoral | Attributes more or less normal |
| Spines 0 | |
| Soft-rays 10 - 12 | |
| Pelvics | Attributes more or less normal |
| Position abdominal before origin of D1 | |
| Spines | |
| Soft-rays |