catch fish
撈 centers on the action of scooping or dragging to catch fish from water.
撈 combines 扌 (hand) with 勞, which likely contributes the sound and the idea of labor or effort, suggesting the manual work of catching fish.
The hand radical 扌 beside 勞 (labor) shows the effort of using one's hands to scoop fish from the water.
For ロウ, imagine a fisherman rowing a boat while scooping fish: row -> ロウ, and the hand 扌 does the labor 勞 of catching fish.
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