bonito
鰹 refers specifically to the bonito fish, a type of tuna-like fish important in Japanese cuisine.
鰹 combines 魚 (fish) with 堅, which likely contributes the sound ケン. The character was created to name the bonito fish specifically.
The left side is a fish 魚, and the right side 堅 suggests something firm or hard. Picture a firm, meaty bonito fish: 鰹 is that bonito.
For ケン, imagine Ken the fisherman proudly holding up a freshly caught bonito: Ken -> ケン, and the fish is a bonito.
skipjack tuna (Katsuwonus pelamis); oceanic bonito; victorfish
katsuobushi; pieces of sliced dried bonito
the first bonito of the season
carpet beetle (Anthrenus verbasci)
black carpet beetle (Attagenus unicolor japonicus)
frigate tuna (Auxis spp.)
striped bonito (Sarda orientalis); Mexican bonito
temptation one can't resist; setting a wolf to mind the sheep; trusting a cat with milk
butterfish (any fish of family Stromateidae, esp. species Pampus punctatissimus); harvestfish; rudderfish
bonito caught in autumn
Pacific pomfret (Brama japonica)
dried bonito shavings
(dried) bonito stock
salted fermented bonito guts
Portuguese man-of-war (Physalia physalis)
log on the roof of a shrine set perpendicular to the ridgepole
dermestid beetle
Eden's whale (Balaenoptera edeni); Bryde's whale
booby (esp. the brown booby, Sula leucogaster); gannet