Fish belonging to the taxonomic order Osteichthyes, also known as the "bony fish," have skeletons that are predominantly made of bone tissue.
In contrast to them, the Chondrichthyes have skeletons that are predominantly made of cartilage.
Bony fish are regarded as belonging to the class Osteichthyes, which is further classified into two primary categories: fish with ray fins, called Actinopterygii.
The group of fishes known as lobe-finned fishes, or Sarcopterygii, contains lungfish and coelacanths.
Sarcopterygii (lobe-finned fishes): It is a clade containing the lungfishes, coelacanths, tetrapods, and their fossil relatives, including the panderichthyids and osteolepiformes.
Actinopterygii (ray-finned fishes): It is a clade containing bony fishes such as lionfish, cod, tuna, and even seahorses.