abalone, puffer fish
鰒 centers on two specific sea creatures: abalone and puffer fish. These are distinct animals, but the kanji covers both, likely due to historical usage overlap.
鰒 combines 魚 (fish) with 复, which likely contributes the sound. The character was used historically for both abalone and puffer fish, though the exact semantic development is uncertain.
The left side is 魚 (fish), and the right side 复 looks like a complex shell or a puffed shape. Picture a fish that can be a shelled abalone or a puffed-up puffer fish.
For フク, imagine a puffer fish puffing up and making a 'fuku' sound as it inflates: fuku -> フク, and the fish shape on the left reminds you it's a sea creature.