codfish
鱨 refers specifically to a codfish, a type of fish. The meaning is narrow and concrete, centered on this particular fish species.
鱨 combines the fish radical 魚 with 嘗, which likely provides the sound. The character was created to name a specific fish, the codfish.
The left side 魚 means fish, and the right side 嘗 looks like a complex container. Imagine a codfish being stored in a special container after being caught.
For ショウ, picture a codfish being shown off at a fish market: 'show' -> ショウ, and the fish is the star of the display.