fish bladder
鰾 refers specifically to the swim bladder of a fish, the internal organ that helps control buoyancy.
鰾 combines 魚 (fish) with 票, which likely provides the sound ヒョウ. The character was created to name the fish bladder, a specialized fish organ.
The left side 魚 means fish, and the right side 票 looks like a floating ticket. Picture a fish using a ticket-shaped bladder to float at the right depth.
For ヒョウ, imagine a fish bladder floating like a buoy: buoy -> ヒョウ, and the fish uses it to stay afloat.