| Main Ref. | Cohen, D.M., T. Inada, T. Iwamoto and N. Scialabba, 1990 |
| Appearance refers to | |
| Bones in OsteoBase |
| Specialized organs | |
| Different appearance | |
| Different colors | |
| Remarks |
| Striking features | |
| Body shape lateral | elongated |
| Cross section | |
| Dorsal head profile | |
| Type of eyes | |
| Type of mouth/snout | |
| Position of mouth | |
| Type of scales | |
| Diagnosis |
Caudal fin margin usually concave. Color is silvery on back, silvery whitish on belly. M. gayi gayi and M. gayi peruanus differ by the total number of vertebrae, total number of gill rakers and relative length of head (Ref. 1371). |
| Ease of Identification |
| Lateral Lines | 1 Interrupted: No |
| Scales on lateral line | 106 - 130 |
| 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 | |
| Fins number | 2 |
| Finlets No. | Dorsal 0 - 0 |
| Ventral 0 - 0 | |
| Spines total | 1 - 1 |
| Soft-rays total | 45 - 54 |
| Adipose fin | absent |
| Attributes | other (see remark); more or less normal |
| Fins number | 1 |
| Spines total | 0 - 0 |
| Soft-rays total | 36 - 42 |
| Pectoral | Attributes more or less normal |
| Spines | |
| Soft-rays | |
| Pelvics | Attributes more or less normal |
| Position thoracic before origin of D1 | |
| Spines | |
| Soft-rays |