The Fate of the Great Grand Nephew of Lord Poseidon
It wasn't at that actual moment of sleep nor was it every time he closed his eyes. It was only during those seconds when he was still awake but sleep was inevitable that the fish would appear.
With his head on his pillow and his eyes shut they would slither out from under his bed, wriggle from slightly opened closet doors and swim from under lamp shades. There was no surprising them, he had tried. To avoid them was to avoid sleep, which he had also tried.
So as he slipped away into his nightly rest he could feel the weight of the ocean on his chest. The morning woke him gasping for breath, exhausted, with seaweed caught in his throat and salt crusted on his eyelids.