1. Their endoskeleton is made up of bones. Therefore, the body structure is developed.
2. Body covered with ganoid or cosmed scales. It acts as an exoskeleton.
3. The body consists of paired fins with fleshy segments which are suitable for locomotion.
4. Their caudal fins are diphycircal in nature. It acts as a locomotor organ.
5. They have jaw teeth. Teeth are covered by enamel
6. There are air sacs in the body. It holds air and helps the fish float and breathe.
7. They are unisexual and occur either externally or internally