There are two types of fish that can be quite difficult to tell apart. Firstly cartilaginous fish have skeletons composed of cartilage. Secondly, bony fish have, yes you guessed it, bone skeletons! Their biological classifications are Chondrichthyes and Osteichthyes respectively. Chondrichthyes and Osteichthyes There are more than 20,000 fish species in the world of the … Continued