In Chinese culture, the carp (鲤鱼) symbolizes perseverance and success. The legend of 鲤鱼跳龙门 (carp leaping over the dragon gate) represents achieving great things through effort, often applied to passing imperial exams or gaining promotion.
Left fish radical - the indexing radical, pictograph of a fish on its side with head, body and tail. Anchors 鲤 in the freshwater-fish family with 鲫 (crucian carp), 鲈 (perch), 鲨 (shark). Carp are the prototypical Chinese pond fish - both food and auspicious symbol of perseverance.
Right side 里 supplies the sound directly (lǐ to lǐ, exact match). Same phonetic anchors a broad family: 理 (reason), 厘 (decimal), 哩 (interjection). The 'village / interior' meaning is incidental, though carp do thrive in village ponds - a useful mnemonic for the radical-phonetic pair.
