鳘 is rarely used alone; it names the cod and appears mainly in 鳘鱼. It joins 敏 for the sound with the fish radical 鱼 for the meaning - the same phonetic-plus-fish pattern seen across most fish names like 鲤 and 鲨.
register
Specialist and bound - found mostly in the fish name 鳘鱼, not as a free word.
