Ichthyology

Ichthyology is the zoological branch focused on the study of fish, which encompasses bony fish (Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha). As of March 2025, FishBase reports that 35,800 species of fish have been described.

The human drive to obtain food, clothing, and tools gave rise to the study of fish. According to ichthyologist Michael Barton, the earliest ichthyologists were hunter-gatherers who learned which fish were most useful, where to find them in abundance, and when they were most available. Early cultures expressed this knowledge through abstract but recognizable art forms, with the practice dating back to the Upper Paleolithic Revolution.

From around 1500 BC to 40 AD, informal scientific descriptions of fish appeared in the Judeo-Christian tradition. The Old Testament’s kashrut laws prohibited eating fish without scales or appendages. Scholars studying the Sea of Galilee have identified native fish species harvested by fishermen like the apostle Peter, including cyprinids from the genera *Barbus* and *Mirogrex*, and cichlids from the genus *Sarotherodon*.

Between 335 BC and 80 AD, Aristotle brought ichthyology into formal science. From 333 to 322 BC, he created the earliest taxonomic classification of fish, accurately describing 117 Mediterranean species and noting anatomical and behavioral differences between fish and marine mammals. After his death, his pupil Theophrastus wrote a treatise on amphibious fish. The Romans, though less scientifically inclined, wrote extensively on fish. Pliny the Elder compiled Greek ichthyological works, including verified facts like the sawfish and dubious ones like the mermaid. His work was the last major contribution until the European Renaissance.

Modern ichthyology began with three 16th-century scholars: Hippolito Salviani, Pierre Belon, and Guillaume Rondelet. Their research was based on actual investigation rather than ancient accounts, which popularized their findings. Rondelet’s *De Piscibus Marinis* was the most influential, identifying 244 fish species.

During the 16th and 17th centuries, advances in navigation and shipbuilding during the Renaissance led to an era of exploration and colonization, which spurred naturalism. In 1648, Georg Marcgrave of Saxony published *Naturalis Brasilae*, describing 100 fish species from the Brazilian coast. In 1686, John Ray and Francis Willughby released *Historia Piscium*, a scientific work covering 420 fish species, 178 of which were new. The fish were arranged in a provisional classification system.

Carl Linnaeus, the father of modern taxonomy, further developed this classification into a systematic approach for studying organisms, including fish. However, his colleague Peter Artedi is called the father of ichthyology for his essential contributions. Artedi helped refine Linnaeus’s taxonomic principles and recognized five additional fish orders: Malacopterygii, Acanthopterygii, Branchiostegi, Chondropterygii, and Plagiuri. He also created standard methods for counting and measuring anatomical features still used today. Another Linnaeus associate, Albertus Seba, a wealthy Amsterdam pharmacist, assembled a fish collection and invited Artedi to use it. In 1735, Artedi drowned in an Amsterdam canal at age 30. Linnaeus posthumously published Artedi’s manuscripts as *Ichthyologia, sive Opera Omnia de Piscibus* (1738). Linnaeus’s taxonomic refinements led to binomial nomenclature, used by modern ichthyologists. He revised Artedi’s orders, emphasizing pelvic fins: fish lacking them were placed in the order Apodes; those with abdominal, thoracic, or jugular pelvic fins were termed Abdominales, Thoracici, and Jugulares, respectively. These changes were not based on evolutionary theory, so it took over a century for Charles Darwin to provide the intellectual foundation showing that similarity in taxonomic features reflects phylogenetic relationships.

Near the start of the 19th century, Marcus Elieser Bloch of Berlin and Georges Cuvier of Paris worked to consolidate ichthyological knowledge. Cuvier’s *Histoire Naturelle des Poissons*, published in 22 volumes from 1828 to 1849, summarized all available information, describing 4,514 fish species, 2,311 of which were new to science. It remains one of the most ambitious scientific treatises of the modern era.