lizard fish
鱠 centers on a specific type of fish: the lizard fish. It is a narrow, concrete term without broader abstract extensions.
鱠 combines the fish radical 魚 with the phonetic component 會, which likely indicates the sound. The character was used historically for a type of fish, but the exact origin of the association with lizard fish is uncertain.
The left side is a fish 魚, and the right side 會 looks like a complex meeting. Imagine a strange fish that looks like a lizard, meeting the eye of a surprised fisherman.
For カイ, picture a lizard fish swimming in a cove (cove sounds like カイ). The cove is its hidden meeting place.