Glossary of ichthyologyThis glossary of ichthyology is a list of definitions of terms and concepts used in ichthyology, the study of fishes.
FisheryFishery 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 farms, both in freshwater waterbodies (about 10% of all catch) and the oceans (about 90%). About 500 million people worldwide are economically dependent on fisheries.
ElasmobranchiiElasmobranchii () 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 having five to seven pairs of gill slits opening individually to the exterior, rigid dorsal fins and small placoid scales on the skin.
SharkPredatory cartilaginous fishesSharks are a group of elasmobranchcartilaginous fishes characterized by a riblessendoskeleton, 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 divisionSelachii and are the sister group to the Batomorphi (rays and skates).
HagfishClass of eel-shaped, slime-producing animalHagfish, of the classMyxini (also known as Hyperotreti) and orderMyxiniformes, are eel-shaped jawless fish (occasionally called slime eels). Hagfish are the only known living animals that have a skull but no vertebral column; however, they do have rudimentary vertebrae.
ActinopterygiiActinopterygii ( ; from Ancient Greek ἀκτίς (aktís) 'ray, beam' and πτέρυξ (ptérux) 'wing, fins'), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that constitutes nearly 99% of the over 30,000 living species of fish. The vast majority of extant actinopterygian species are teleosts, and by species count they dominate the subphylum Vertebrata, comprising over 50% of all living vertebrates.
LampreyClass of jawless fishSea lamprey, Petromyzon marinusMouth of a sea lamprey, Petromyzon marinusMedian section of lamprey demonstrating internal anatomyMicroscopic cross section through the pharynx of a larva from an unknown lamprey speciesLampreys (sometimes inaccurately called lamprey eels) are a group of jawless fish composing the orderPetromyzontiformes, sole order in the classPetromyzontida. The adult lamprey is characterized by a toothed, funnel-like, sucking mouth.
Taxonomy (biology)In biology, taxonomy (from Ancient Greek (taxis)'arrangement' and ()'method') is the scientific study of naming, defining (circumscribing) and classifying groups of biological organisms based on shared characteristics. Modern approaches prioritize common ancestry and evolutionary relationships.
Fish anatomyFish anatomy is the study of the form or morphology of fish. It can be contrasted with fish physiology, which is the study of how the component parts of fish function together in the living fish.
IchthyologyIchthyology 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 2025.
FishA fish is an aquatic, anamniotic, gill-bearing vertebrateanimal with a tough cranium to protect the brain, but lacking limbs with digits. Fish can be grouped into the more basaljawless fish and the more common jawed fish, the latter including all livingcartilaginous and bony fish, as well as the extinct placoderms and acanthodians.
TeleostDivision or infraclass of fishesTeleostei (; from Ancient Greek τέλειος (téleios) 'complete' and ὀστέον (ostéon) 'bone'), members of which are known as teleosts (), is, by far, the largest group of ray-finned fishes (class Actinopterygii), with 96% of all extant species of fish.
FisheryFishery 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 farms, both in freshwater waterbodies (about 10% of all catch) and the oceans (about 90%). About 500 million people worldwide are economically dependent on fisheries.ElasmobranchiiElasmobranchii () 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 having five to seven pairs of gill slits opening individually to the exterior, rigid dorsal fins and small placoid scales on the skin.SharkPredatory cartilaginous fishesSharks are a group of elasmobranchcartilaginous fishes characterized by a riblessendoskeleton, 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 divisionSelachii and are the sister group to the Batomorphi (rays and skates).HagfishClass of eel-shaped, slime-producing animalHagfish, of the classMyxini (also known as Hyperotreti) and orderMyxiniformes, are eel-shaped jawless fish (occasionally called slime eels). Hagfish are the only known living animals that have a skull but no vertebral column; however, they do have rudimentary vertebrae.ActinopterygiiActinopterygii ( ; from Ancient Greek ἀκτίς (aktís) 'ray, beam' and πτέρυξ (ptérux) 'wing, fins'), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that constitutes nearly 99% of the over 30,000 living species of fish. The vast majority of extant actinopterygian species are teleosts, and by species count they dominate the subphylum Vertebrata, comprising over 50% of all living vertebrates.LampreyClass of jawless fishSea lamprey, Petromyzon marinusMouth of a sea lamprey, Petromyzon marinusMedian section of lamprey demonstrating internal anatomyMicroscopic cross section through the pharynx of a larva from an unknown lamprey speciesLampreys (sometimes inaccurately called lamprey eels) are a group of jawless fish composing the orderPetromyzontiformes, sole order in the classPetromyzontida. The adult lamprey is characterized by a toothed, funnel-like, sucking mouth.Taxonomy (biology)In biology, taxonomy (from Ancient Greek (taxis)'arrangement' and ()'method') is the scientific study of naming, defining (circumscribing) and classifying groups of biological organisms based on shared characteristics. Modern approaches prioritize common ancestry and evolutionary relationships.Fish anatomyFish anatomy is the study of the form or morphology of fish. It can be contrasted with fish physiology, which is the study of how the component parts of fish function together in the living fish.IchthyologyIchthyology 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 2025.FishA fish is an aquatic, anamniotic, gill-bearing vertebrateanimal with a tough cranium to protect the brain, but lacking limbs with digits. Fish can be grouped into the more basaljawless fish and the more common jawed fish, the latter including all livingcartilaginous and bony fish, as well as the extinct placoderms and acanthodians.TeleostDivision or infraclass of fishesTeleostei (; from Ancient Greek τέλειος (téleios) 'complete' and ὀστέον (ostéon) 'bone'), members of which are known as teleosts (), is, by far, the largest group of ray-finned fishes (class Actinopterygii), with 96% of all extant species of fish.*As an Amazon Associate I earn from qualifying purchases.