鲻

Left-side fish radical - pictograph of a fish with head at top, body in the middle, and tail-fin below. The indexing radical for the fish family: 鲤 carp, 鲨 shark, 鲸 whale, 鲈 perch. Here it tags 鲻 as a fish, specifically the grey mullet, a coastal estuarine species widely eaten across East Asia.

Right side 甾 supplies the sound - zī read straight across with no shift. 甾 itself is an old character for tangled-up fallow land or a kind of basket; the link to mullet is purely phonetic. A faint visual echo though: the boxy zigzag shape of 甾 mirrors the dark transverse bars running along the side of a grey mullet.