is one piece episode 531 filler?

The episode starts out with a flashback, showing how Ishilly and her friends were captured by Caribou. The flashback ends with Caribou saying how he should thank the Straw Hats for taking him to "Treasure Island".

Back in the present, Fukaboshi and his brothers, along with their guards, are talking to Madam Shyarly about her prediction. Fukaboshi, after discussing the matter with some of the Fish-Man islanders, decides to find and take the Straw Hats into custody.

Meanwhile, the Straw Hats, and their friends, discuss amongst themselves and King Neptune.