Fish measurement is the measuring of individual fish and various parts of
their anatomies, for data used in many areas of
ichthyology
Ichthyology is the branch of zoology devoted to the study of fish, including bony fish (Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha). According to FishBase, 35,800 species of fish had been described as of March 2 ...
, including
taxonomy
image:Hierarchical clustering diagram.png, 280px, Generalized scheme of taxonomy
Taxonomy is a practice and science concerned with classification or categorization. Typically, there are two parts to it: the development of an underlying scheme o ...
and
fishery
Fishery can mean either the enterprise of raising or harvesting fish and other aquatic life or, more commonly, the site where such enterprise takes place ( a.k.a., fishing grounds). Commercial fisheries include wild fisheries and fish far ...
biology.
Overall length
Standard length (SL) is the length of a fish measured from the tip of the snout to the posterior end of the last vertebra or to the posterior end of the midlateral portion of the
hypural plate. This measurement excludes the length of the
caudal (tail) fin.

Total length (TL) is the length of a fish measured from the tip of the snout to the tip of the longer lobe of the caudal fin, usually measured with the lobes compressed along the midline. It is a straight-line measure, not measured over the curve of the body.
Standard length measurements are used with
Teleostei
Teleostei (; Ancient Greek, Greek ''teleios'' "complete" + ''osteon'' "bone"), members of which are known as teleosts (), is, by far, the largest group of ray-finned fishes (class Actinopterygii), with 96% of all neontology, extant species of f ...
(most
bony fish
Osteichthyes ( ; ), also known as osteichthyans or commonly referred to as the bony fish, is a Biodiversity, diverse clade of vertebrate animals that have endoskeletons primarily composed of bone tissue. They can be contrasted with the Chondricht ...
), while total length measurements are used with Myxini (
hagfish
Hagfish, of the Class (biology), class Myxini (also known as Hyperotreti) and Order (biology), order Myxiniformes , are eel-shaped Agnatha, jawless fish (occasionally called slime eels). Hagfish are the only known living Animal, animals that h ...
), Petromyzontiformes (
lamprey
Lampreys (sometimes inaccurately called lamprey eels) are a group of Agnatha, jawless fish comprising the order (biology), order Petromyzontiformes , sole order in the Class (biology), class Petromyzontida. The adult lamprey is characterize ...
s) and usually
Elasmobranchii
Elasmobranchii () is a subclass of Chondrichthyes or cartilaginous fish, including modern sharks ( division Selachii), and batomorphs (division Batomorphi, including rays, skates, and sawfish). Members of this subclass are characterised by h ...
(
shark
Sharks are a group of elasmobranch cartilaginous fish characterized by a ribless endoskeleton, dermal denticles, five to seven gill slits on each side, and pectoral fins that are not fused to the head. Modern sharks are classified within the ...
s and
rays), as well as some other fishes.
Total length measurements are used in
slot limit and
minimum landing size
The minimum landing size (MLS) is the smallest fish measurement at which it is legal to keep or sell a fish. The MLS depends on the species of fish. Sizes also vary around the world, as they are legal definitions which are defined by the local regu ...
regulations.
Fishery biologists often use a third measure in fishes with forked tails, called Fork length (FL), the length of a fish measured 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.
Fin lengths and eye diameter
Other possible measurements include the lengths of various fins, the lengths of fin bases and the diameter of the eye.
File:Black Drum Length vs. Age.png,
File:Red Snapper Length vs Age.png,
See also
*
Ichthyology terms
*
Standard weight in fish
References
External links
Diagram of fish measurements- Florida Museum of Natural History Ichthyology Department
{{DEFAULTSORT:Fish Measurement
Ichthyology
Fishkeeping
Fish anatomy
Fisheries science