・ 音 コ
Sino-Vietnamese: cá
亻(person) for meaning, 固 (solid, enclosed) for sound: each one boxed off separately. Individual, and the general counter for objects — 三個.
Stroke data: KanjiVG (CC BY-SA 3.0) — kanjivg.tagaini.net
りんごを三個買いました。 (りんごをさんこかいました)
I bought three apples.