Cartilaginous fishes

1. They have a cartilaginous endoskeleton.

2. They contain 5-7 pairs of gill slits.

3. An operculum is absent in them.

4. Their mouth is ventral in position.

5. Their caudal fin is heterocercal.

6. Swim bladder is absent in them.

Example: Indian shark, electric ray, etc.

Bony fishes

1. They have a bony endoskeleton.

2. They contain four pairs of gill slits.

3. Their gill slits are covered with an operculum.

4. Their mouth is terminal in position.

5. Their caudal fin is homocercal.

6. Air bladder is usually present in them.

Example. Carp, sea horse, etc.