The vast majority of extant (living) species of fishes are of the bony fishes in the group Osteichthyes. And of the 30,000+ species within Osteichthyes, nearly all of them are ray-finned fishes, or actinopterygians; there are only 8 living species of lobe-finned fishes, or sarcopterygians: 6 lungfishes and 2 coelacanths.

More to come.

This video explains the need-to-know features of most fishes. More to come. 

Table of Contents - The Fishes