type of herring
鯆 refers to a type of herring, a specific fish. The meaning is narrow and concrete, centered on this particular marine animal.
鯆 combines 魚 (fish) with 甫, which likely contributes the sound. The character was created to name a specific fish.
The left side 魚 means fish, and the right side 甫 looks like a net or a container. Picture a net full of herring: 鯆 is that type of herring.
For フ, imagine a herring jumping out of the water and making a 'foo' sound as it splashes back: foo -> フ, and the fish is a herring.