Fish are commonly measured in several ways. Taxonomists use the following two measurements for overall fish length:
Standard length (SL) refers to the length of a fish measured from the tip of the snout to the end of the caudal peduncle. This measurement excludes the caudal fin.
Total length (TL) refers to the length from the tip of the snout to the tip of the caudal fin. It is a straight-line measure, not measured over the curve of the body.
Standard length measurements are used with Teleostei (most bony fish), while total length measurements are used with Myxini (hagfish), Petromyzontiformes (lampreys), and (usually) Elasmobranchii (sharks and rays), as well as some other fishes.
In addition, fisheries biologists often use a third measure, fork length, in fishes with forked tails. This measure is the length from the tip of the snout to the end of the middle caudal fin rays and is used in fishes in which it is difficult to tell where the vertebral column ends.
Copyright: Wikipedia information about Fish measurement – This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Fish measurement". More from Wikipedia