| Cartilaginous fishes | Bony fishes |
| 1. These are marine farms. | 1. These are live in all kinds of aquatic habits. |
| 2. Endoskeleton made by cartilaginous. | 2. Endoskeleton made by bone. |
| 3. Body covered by plocoid scales. | 3. Body covered by cosmoid, ganoid, cycloid or ctenoid scales. |
| 4. Caudal fin is heterocercal. | 4. Caudal fin is homocercal. |
| 5. Operculum absent. | 5. Operculum present. |
| 6. Air bladder absent. | 6. Air baldder present. |
| 7. Gills are lamelliform and are five to seven in each side. | 7. Gills are filamentous and are four in each side. |
8. These are ureotelic.
Ex : Scoliodon, Pristic, Torpedo | 8. These are mostly ammono- telic.
Ex : Catla, Labeo, Exocetus, Hippocampus. |
