is one piece episode 20 filler?

Johnny explains that after his bounty hunting partner, Yosaku, had fallen ill from an unknown disease, they had stopped at a rock so Yosaku could rest. However, the rock was targeted by Luffy's cannon, which he assumed to be a deliberate attack.

The crew take an ill Yosaku onboard and Nami diagnoses him with scurvy, a disease caused by a vitamin C deficiency. After treating his illness by feeding him lime juice, they bring him inside to rest.

The crew decide they need a crew member specializing in cooking to tend to their dietary needs.