noun / verb
fish
FISH/fɪʃ/
An aquatic animal with gills and usually fins.
A silver fish swims beneath the clear surface of the pond.

Etymology
Old English fisc could name aquatic animals generally, not just the gilled, finned vertebrates meant here. That broader usage survives in compounds such as shellfish and starfish.
In context
a fish with an infection usually ends up with 1 female in its mouth and as many as 5 males in its gills!
More examples
- We fished from the old pier.
- The lake contains several kinds of fish.
- She photographed colorful fishes on the reef.
Forms
fish · fishes · fished · fishing · fishs
fisher noun — Someone who catches fish