bream, minnow
鱮 centers on small freshwater fish: specifically a bream or minnow. The two given meanings are closely related as types of small fish.
鱮 combines the fish radical 魚 with 與, which likely contributes the sound. The character was created to name specific fish species.
The fish radical 魚 on the left tells you it's a fish. The right side 與 looks like a complicated net or trap, so imagine a small bream or minnow caught in a finely woven net.
For ショ, picture a small fish being shown off by a proud angler: 'Show!' -> ショ, as they display the tiny bream.