Definition
An animal that inhabits water, breathes by means of gills, swims by means of fins, and reproduces by depositing eggs (oviparous). In legal contexts, fish are classified as ferae naturae — wild animals by nature — meaning no person holds private property in them by virtue of their existence alone. Property rights in fish arise only through capture and possession. If a captured fish escapes and returns to its natural state, the captor's property interest is extinguished.
Beyond the biological individual, the term carries broader legal significance in regulatory and constitutional law, where "fish" or "fisheries" denotes a resource subject to public ownership, state sovereignty, and federal management authority.
Common Language
Modern common usage (Wiktionary): A typically cold-blooded vertebrate animal that lives in water, moving with the help of fins and breathing with gills.
Historical common usage (Webster's 1913): A counter, used in various games. (Webster's 1913 also carries the biological sense; this secondary entry reflects a now-archaic token or chip used in card games and tallying.)
The biological common meaning and the legal meaning track each other closely at the level of the individual animal. The divergence is not in what a fish is, but in what legal consequences attach to that classification. Common usage treats fish as ordinary objects subject to ownership. Legal classification as ferae naturae means fish are not ownable property until reduced to possession — a distinction with real consequences for trespass, theft, conversion, and regulatory standing.
Common Confusion
Fish vs. Shellfish and Crustaceans: Many regulatory schemes define "fish" broadly to include shellfish, crustaceans, and other aquatic species, departing from the biological definition used in historical dictionaries. Researchers using historical sources should not assume the narrower biological classification governs a given statute. Modern fisheries law routinely expands "fish" by explicit definition.
Ferae Naturae vs. Ownership: The classification of fish as ferae naturae is sometimes misread as meaning the state owns fish. The traditional common law rule is subtler: no private party owns unconfined fish; the state holds them in trust for the public, not as proprietary owner in the strict sense. This distinction matters in takings and sovereign immunity analysis.
Why It Matters in Research
The legal significance of "fish" has shifted substantially from the common law baseline to modern statutory and regulatory frameworks, and researchers moving between historical and contemporary sources need to track that shift carefully.
At common law, the ferae naturae doctrine governed everything: no property until capture, property lost upon escape. Bouvier states this cleanly and it remains the foundation. But modern federal and state fisheries law builds an extensive regulatory structure on top of — and sometimes in tension with — that foundation. Statutes like the Magnuson-Stevens Fishery Conservation and Management Act operate in federal waters and redefine "fish" by explicit statutory language, often encompassing species the common law definition would not recognize.
Researchers in the Law Mind corpus should note:
The term "fish commissioner" appears in Black's (2nd Ed.), reflecting a now-reorganized federal administrative structure. References to fish commissioners in historical sources point to an institutional lineage that evolved into the U.S. Fish and Wildlife Service and NOAA Fisheries — context essential for tracing regulatory authority.
State sovereign ownership claims over fish are grounded in public trust doctrine, not fee ownership. Cases and treatises invoking state "ownership" of fish are often using that term loosely. The legal theory shifted significantly after federal preemption questions arose in the twentieth century.
Historical dictionary definitions uniformly use the narrow biological definition (gills, fins, oviparous). Modern regulatory sources frequently use a broadened statutory definition. A historical source's treatment of fish law may simply not apply to shellfish, salmon farming, or aquaculture — topics now governed by distinct legal regimes.
Researchers tracing property rights in fish through equity or admiralty sources will encounter the ferae naturae principle applied differently depending on whether the fish are in navigable waters, private ponds, or tidal zones. Each setting generates distinct precedent.
Historical Dictionary Support
Black's (1st Ed.) and Black's (2nd Ed.) offer nearly identical biological definitions, with Black's (2nd Ed.) adding the reference to "Fish commissioner" as a public officer created by act of Congress. Bouvier provides the most legally useful historical statement: fish are ferae naturae, no property attaches until capture, and the captor's interest dissolves upon the animal's escape. All three sources agree on this foundational classification.
What historical dictionaries do not address: aquaculture and fish farming (where fish are confined and ownership is continuous); the public trust doctrine as a constitutional constraint on state alienation of fishery rights; federal preemption of state fish regulation in navigable and coastal waters; and international fisheries law, including exclusive economic zone concepts entirely post-dating these sources.
The oviparous qualifier in historical definitions is biologically imprecise by modern standards — some fish bear live young — but this imprecision has never generated significant legal dispute, since regulatory definitions do not hinge on reproductive method.
Jurisdictional Note
State law governs fish in inland waters; federal law governs fish in the exclusive economic zone (three to two hundred nautical miles offshore). Coastal and tidal waters involve overlapping state and federal claims that vary by state and remain a recurring source of litigation. Some states have codified the public trust doctrine in ways that restrict private aquaculture rights; others actively promote it.
Encyclopedia Cross-Reference
Wildlife Law; Property in Wild Animals; Public Trust Doctrine