shoal

(noun) a sandbank in a stretch of water that is visible at low tide.

(noun) a stretch of shallow water. Synonyms: shallow.

(noun) a large group of fish. Synonyms: school. Example: "A school of small glittering fish swam by."

(verb) make shallow. Synonyms: shallow. Example: "The silt shallowed the canal."

(verb) become shallow. Synonyms: shallow. Example: "The lake shallowed over time."