You can improvise hooks from all kinds of materials.
 |
| Pin |
 |
| A thorn |
 |
| A bunch of thorns |
 |
| Nails |
 |
| Bone |
 |
| Wood |
Large hooks will catch large fish, but small ones catch large and small. A rod is not essential (you can fish with a handline) but it makes it easier to land fish and cast away from the bank.