Do schools shift depth during the day?

Yes — a daily flat-to-deep breathing pattern, driven by light. In low morning sun schools often start on the shallow inside edge of a flat; as midday light strengthens (and in summer, as the shallows warm past comfort) the grazing front slides toward the deep edge and adjacent basin; late afternoon can bring a push back up before the hard dusk shutdown. The swing might be 2–3 m (6–10 ft) on an inland lake and much more on big clear water. Practically: if a morning depth dies at 11 a.m., check one contour deeper before you check anywhere else.

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