There are two that come to mind. Malibu Fish & Seafood is probably the one you mean (given the location you describe) and the other, farther up the coast, is Neptune's Net.
Malibu Fish & Seafood
25653 Pacific Coast Hwy, Malibu, CA 90265
Neptune's Net Seafood
42505 Pacific Coast Hwy, Malibu, CA 90265