Superman: The Animated Series (1996)

S3E9 A Fish Story

In Metropolis, an assault from marine creatures unfolds as Lex Luthor has successfully taken Aquaman hostage. With their ruler imprisoned, the ocean's denizens rise up, wreaking havoc on the city. As chaos ensues, the citizens of Metropolis are left to face the fury of the sea, while Superman and his allies scramble to devise a plan to rescue Aquaman and restore order before it’s too late.