ichthy

Ichthy is a combining form used in science and related disciplines to indicate a relationship to fish. It appears in a wide range of terms that name groups of organisms, studies, and anatomical or physiological concepts tied to fish. The form is derived from the Greek word ikhthys, meaning fish, and has several spellings in English, most commonly ichthy- and ichthyo-.

In biology and paleontology, ichthy-related terms are widespread. Ichthyology is the scientific study of fish, while ichthyofauna refers to the fish species present in a given region. The prefix also features in names of extinct and living aquatic animals, such as ichthyosaurs, a group of marine reptiles whose name literally means “fish lizards.” Other examples include ichthyoid (resembling a fish) and ichthyopelagic (related to fish-dwelling zones in the water column). In medicine, ichthy- appears in terms like ichthyosis, a family of skin disorders characterized by dry, scaly skin, named for its fish-scale-like appearance.

The use of ichthy as a root is primarily linguistic, serving to form terms rather than standing alone as a word with independent meaning. Spelling variations reflect common patterns in Greek-derived scientific terminology, with ichthy- and ichthyo- both functioning as flexible prefixes that attach to different bases to describe fish-related biology, anatomy, and pathology. See also ichthyology, ichthyofauna, and ichthyosis for representative applications.