Fish found in shallow water (5)

I believe the answer is:

shoal

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'shallow water' is the definition.
(I've seen this before)

I cannot understand how the rest of the clue works.

(Other definitions for shoal that I've seen before include "Collection of fish" , "shallow water" , "Mob" , "Swarm of fish" , "A great number of fish swimming together" .)

I've seen this clue in The Globe and Mail.

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