sole or flounder
魬 centers on a type of flatfish: a sole or flounder. The meaning is specific to this fish, with no broader conceptual extensions.
魬 combines 魚 (fish) with 反, which likely contributes the sound ハン. The character was created to name a specific flatfish.
The left side 魚 means fish, and the right side 反 can suggest something flat or flipped. Picture a flatfish like a sole or flounder that looks like a flipped, flattened fish.
For ハン, imagine a half-flat fish: half -> ハン, and the flatfish is like a fish cut in half.