Fish Is Not a Scientific Category
A fish is a cold-blooded water animal with gills. Biologists have found the group impossible to define cleanly.
A fish is a cold-blooded aquatic animal with gills and fins. As a biological grouping it does not hold together: a lungfish is more closely related to a cow than to a salmon, so any group containing both lungfish and salmon must also contain every land vertebrate. Some biologists say there is no such thing as a fish, meaning the category is not a branch of the family tree. The word survives because it describes a way of living rather than an ancestry.
- An aquatic animal. *A shoal of fish.*
- Plural fish or fishes. *Three fish.*
- To catch fish. *Fishing.*
- Fishy — suspicious. *Something fishy.*
- Old English — *fisc*. *The source.*
Word forms
| Form | Word | Example |
|---|---|---|
| Noun | fish | A fish. |
| Plural | fish | Six fish. |
| Plural | fishes | Several fishes. |
| Verb | fish | Fishing. |
| Adjective | fishy | Fishy. |
- The net held forty fish.Animals.
- Fishes means several species.Plural.
- A lungfish is closer to a cow.Fact.
Why fish is not a clean category
- A lungfish is more closely related to mammals than to a salmon
- Any group with both must also include every land vertebrate
- Such a group is called paraphyletic, a branch with pieces removed
- Biologists use narrower terms like ray-finned or cartilaginous fish
- The everyday word describes a way of life, not an ancestry
Old English *fisc*, of Germanic origin, related to Latin *piscis*.
Is fish a real biological group?
Not a clean one. A lungfish is more closely related to a cow than to a salmon, so the group leaves out descendants it should contain.
Is the plural fish or fishes?
Fish for several individuals. Fishes is used for several different species.