sillaginoid, (kokuji)
鱚 is a Japanese kokuji for a specific fish, the sillaginoid (whiting). Its meaning is narrow and concrete, referring only to this fish.
鱚 is a Japanese kokuji, created by combining 魚 (fish) with 喜 (joy), likely to name the sillaginoid fish. The exact historical origin is uncertain, but it follows the common pattern of using 魚 as a semantic component for fish names.
A fish (魚) that brings joy (喜) when caught: the sillaginoid is a prized catch, so 鱚 is the joyful fish.
For きす, imagine a fish that you kiss (きす) because it's so joyful: kiss -> きす, and the sillaginoid is the fish you want to kiss.
—
sillago (any fish of genus Sillago, esp. the Japanese whiting, Sillago japonica)
deepsea smelt (Glossanodon semifasciatus)
Japanese whiting (Sillago japonica)
harlequin sandsmelt (Parapercis pulchella)
small-scale whiting (Sillago parvisquamis); blue whiting
black swallower (Chiasmodon niger)