Xena: Warrior Princess (1995)

S5E15 Married with Fishsticks

After Gabrielle accidentally knocks her head and tumbles into the sea, she wakes up with amnesia. A merman approaches her, insisting that she is his beloved wife and the mother of their aquatic children. Desperate to help her remember, he weaves a tale of their life together beneath the waves, hoping to rekindle her lost memories.