Ichthyology in the context of "Compendium"

A fish is an aquatic, anamniotic, gill-bearing vertebrate animal with swimming fins and a hard skull, but lacking limbs with digits. Fish can be grouped into the more basal jawless fish and the more common jawed fish, the latter including all living cartilaginous and bony fish, as well as the extinct placoderms and acanthodians. In a break from the long tradition of grouping all fish into a single class (Pisces), modern phylogenetics views fish as a paraphyletic group which includes all vertebrates except tetrapods. In English, the plural of "fish" is fish when referring to individuals and fishes when referring to species.

Most fish are cold-blooded, their body temperature varying with the surrounding water, though some large, active swimmers like the white shark and tuna can maintain a higher core temperature. Many fish can communicate acoustically with each other, such as during courtship displays. The study of fish is known as ichthyology.

The Indo-Pacific is a vast biogeographic region of Earth. In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the seas connecting the two. The term is especially useful in marine biology, ichthyology, and similar fields, since many marine habitats are continuously connected from Madagascar to Japan and Oceania, and a number of species occur over that range, but are not found in the Atlantic Ocean.

As a distinct marine realm, the region has an exceptionally high species richness, with the world's highest species richness being found in at its heart in the Coral Triangle, and a remarkable gradient of decreasing species richness radiating outward in all directions. The region includes over 3,000 species of fish, compared with around 1,200 in the next richest marine region, the Western Atlantic, and around 500 species of reef building corals, compared with about 50 species in the Western Atlantic.

Herpetology (from Ancient Greek ἑρπετόν herpetón, meaning "reptile" or "creeping animal") is a branch of zoology concerned with the study of amphibians (including frogs, salamanders, and caecilians (Gymnophiona)) and reptiles (including snakes, lizards, turtles, crocodilians, and tuataras). Birds, which are cladistically included within Reptilia, are traditionally excluded here; the separate scientific study of birds is the subject of ornithology.

The precise definition of herpetology is the study of ectothermic (cold-blooded) tetrapods. This definition of "herps" (otherwise called "herptiles" or "herpetofauna") excludes fish; however, herpetological and ichthyological scientific societies often collaborate. For instance, groups such as the American Society of Ichthyologists and Herpetologists have co-published journals and hosted conferences to foster the exchange of ideas between the fields. Herpetological societies are formed to promote interest in reptiles and amphibians, both captive and wild.

Fishes of the World is a standard reference for the systematics of fishes. It was first written in 1976 by the American ichthyologist Joseph S. Nelson (1937–2011). Now in its fifth edition (2016), the work is a comprehensive overview of the diversity and classification of the 30,000-plus fish species known to science.

The book begins with a general overview of ichthyology, although it is not self-contained. After a short section on Chordata and non-fish taxa, the work lists all known fish families in a systematic fashion. Each family is given at least one paragraph, and usually a body outline drawing; large families have subfamilies and tribes described as well. Notable genera and species are mentioned, though the book does generally not deal with the species-level diversity. The complexities of the higher taxa are described succinctly, with many references for difficult points. The book does not contain any color illustrations.

Pupfish are a group of small killifish belonging to ten genera of the family Cyprinodontidae of ray-finned fish. Pupfish are especially noted for being found in extreme and isolated situations. They are primarily found in North America, South America, and the Caribbean region. As of August 2006, 120 nominal species and 9 subspecies were known. Several pupfish species are extinct and most extant species are listed. In the U.S., the most well-known pupfish species may be the Devils Hole pupfish, native to Devils Hole on the Nevada side of Death Valley National Park. Since 1995 the Devils Hole pupfish has been in a nearly steady decline, where it was close to extinction at 35–68 fish in 2013.

The common name is said to derive from the mating habits of the males, whose activities vaguely resemble puppies at play; Carl L. Hubbs, a prominent ichthyologist and one of the first people to take an interest in them, coined the name after he observed their "playful" circling and tussling, which is actually the aggressive behavior of territorial males.

Pierre Belon (1517–1564) was a French traveller, naturalist, writer and diplomat. Like many others of the Renaissance period, he studied and wrote on a range of topics including ichthyology, ornithology, botany, comparative anatomy, architecture and Egyptology. He is sometimes known as Pierre Belon du Mans, or, in the Latin in which his works appeared, as Petrus Bellonius Cenomanus. The Russian physiologist Ivan Pavlov (known for Pavlov's dogs) called him the "prophet of comparative anatomy".

Marcus Elieser Bloch (1723–1799) was a German physician and naturalist who is best known for his contribution to ichthyology through his multi-volume catalog of plates illustrating the fishes of the world. Brought up in a Hebrew-speaking Jewish family, he learned German and Latin and studied anatomy before settling in Berlin as a physician. He amassed a large natural history collection, particularly of fish specimens. He is generally considered one of the most important ichthyologists of the 18th century, and wrote many papers on natural history, comparative anatomy, and physiology.

Incisoscutum is an extinct genus of arthrodire placoderm from the Early Frasnian Gogo Reef, from Late Devonian Australia. The genus contains two species I. ritchiei, named after Alex Ritchie, a palaeoichthyologist and senior fellow of the Australian Museum, and I. sarahae, named after Sarah Long, daughter of its discoverer and describer, John A. Long.

The genus is important in the study of early vertebrates as well-preserved fossilized embryos have been found in female specimens and ossified pelvic claspers found in males. This shows that viviparity and internal fertilization was common amongst these primitive jawed vertebrates, which are outside the crown group Gnathostomata.