Reef madness hit Coney Island Saturday as fishy fidos, crabby kids and nauty sea monsters in G-strings made waves in the annual Mermaid Parade.

“It’s like Christmas for freaks!” said Sarah Almond, 39, of Brooklyn’s Clinton Hill, decked out as a metallic mermaid with a tin-foil Chrysler Building hat.

Hordes of people were drawn to Coney Island for the parade’s 36th year, where “Ruth Wader Finsburg,” merfolk, pirates, octopi and thousands of splashy sea creatures left trails of glitter as they floated along Surf Avenue and the boardwalk.

Singer-songwriter Amanda Palmer and her husband and bestselling author Neil Gaiman were honored as the Queen Mermaid and King Neptune.

“I feel powerful — like I can lure men into the sea,” said Rosie the Riveter-Mermaid Amia Michelina, 32.

The fishy festivities even hooked Paula Yost, 66, and her daughter from all the way in West Virginia. “My mermaid days are over, so now I’m a jellyfish,” Yost said.

“It never gets old,” said mermaid vet Whitney Ward, marching in her 30th parade this year as a purple sea urchin in honor of her friend and celebrity chef Anthony Bourdain, who died this month. “He always made sure I had good sea urchin when we ate out,” Ward said.

One seahorse added: “I feel like this is where all the best people in New York are today!”