Mulgogiro Saranamgi

Could you survive as a fish? Yushin, the president of Saseong Group, is betrayed by his boss and thrown into a lake, left for dead. But a mysterious voice calls out to Yushin underwater. “Would you like to start a new life?” He wakes up to find himself as a slimy, scaly largemouth bass tasked with a plethora of quests to fulfill that ultimately promises him one wish. Will Yushin be able to navigate the waters and find a way to become human again?

(Source: Webtoons)