The scientific study and classification of fish comes under an area of study known as ichthyology. However, before the study of fish can begin, it is very important to define just what a fish is. Most ichthyologists would agree that a fish is an aquatic animal that is covered with scales and breathes by passing water internally over its gills. Fish are also cold-blooded, have fins and contain an internal skeleton.
Modern fish are divided into three different classes, depending on whether they have a bony or soft skeleton and also on whether they have a jaw. The most advanced class of fish are called the Osteichthyes. These fish have both a jaw and a bony skeleton. Most animals that we normally call fish, fall into this category. Next are the Chondrichthyes, which also have a jaw, but lack a bony skeleton. Instead, they have a cartilaginous skeleton. This group of primitive fish includes the sharks, rays and skates. Finally there are the Agnatha, which are a very simple class of fish that lack a jaw. Lampreys and hagfish are the two main examples that fall into this most primitive category. Just about all of the sport fish fall into the first category of bony fishes (Osteichthyes)
A scientific name of a fish is expressed in Latin and contains two words. The first word is the scientific term for the genus, while the second word identifies the species of the fish. All living organisms are scientifically classified within a large hierarchy that begins with kingdom and ends at the species level. Now, that is known how to separate fish into different classes, it will become necessary to break down each “Class” into the various sub-groupings until the genus is determined. This process will require several steps, as “Class” is sub divided into orders and then each order is subdivided into families. From family the hierarchy proceeds to genus or genera, if their is more than one genus within the family.
As an example to illustrate this point, let’s take a look at the black-finned clownfish, which is a small, colorful bony salt-water fish that lives among certain species of anemones. Since the black-finned clownfish is a bony fish, it comes under the class, Osteichthyes. From that point the small fish is placed in the Order, Perciformes, which means perch-like and is a very large division, containing 40% of all bony fishes. Common fish in this order include the perch, bass and sunfish. Next the clown fish is place in the Family, Pomacentridae. This family contains 39 genera of a type of fish, commonly known as damselfish and clownfish. These are the small tropical marine fishes that often end up in aquariums.
The scientific name for a black-finned clownfish is Amphiprion percula. Amphipirion refers to genus and percula describes the species. Today over 20 species of Amphipirion are recognized. The word Amphipirion has two roots, Amphi, which means “all around”(Fr.), and pirion, which means “serrated”(Gr.). The word percula is from the Latin, meaning “little perch”. Every species of fish can be described in this way.