Do you need a filter for a pond without fish?

A filter is not strictly necessary for a pond without fish, but it can still be beneficial. It helps maintain water clarity, reduces debris, and promotes beneficial bacteria that break down organic matter. Without fish, the pond may have less biological waste, so the need for filtration is reduced, but it can still enhance overall water quality and reduce algae growth. Ultimately, the decision depends on the pond's specific conditions and your maintenance preferences.