fish
n. C / Un. a cold-blooded animal that lives in water and breathes through gills. Most have scales and fins to help them swim.
n. a limbless cold-blooded vertebrate animal with gills and fins living wholly in water. Plural forms vary between 'fish' for a single species and 'fishes' for multiple species.
The colorful fish swims in the small tank.
We spent the entire afternoon at the lake trying to catch some fish for dinner.
Marine biologists are currently studying how various species of deep-sea fish adapt to the extreme pressure and total darkness of the ocean floor.
The plural is usually 'fish' when referring to a group of the same kind, but 'fishes' is used in scientific contexts to refer to different species.
I saw three fishes in the pond.I saw three fish in the pond.When counting individuals of the same type, the plural form is identical to the singular.