Rise from Depths: Devouring My Way to Dominion (Dubbed)

Finley Delmar, an unassuming office worker, awakens as an ordinary koi fish spirit, the lowest-rank demon, in a demon-infested lake. With a mysterious System that lets him consume and evolve, plus an uncanny streak of luck, he begins his rise from prey to power, eventually transforming into a mighty dragon that dominates the demon realm and reshapes the fate of every clan beneath the lake.