This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
鱩 combines 魚 (fish) with 雷 (thunder). The exact historical origin is uncertain, but it likely refers to a fish associated with thunder or stormy weather, possibly the sandfish (hatahata) which is caught during thunderstorm seasons.
A fish 魚 beside thunder 雷: imagine a fish that appears when thunder roars, like the hatahata caught in stormy seas.
For はたはた, picture a fisherman shouting 'Ha! Ta! Ha! Ta!' as he hauls in a net full of hatahata fish during a thunderstorm: はたはた.
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