What Are the White Dots on My Goldfish Filters?

Goldfish filters process a variety of biological waste, so it's common for them to develop various residues. Fish owners frequently see white dots on their filters. These can be completely innocuous or can be indicators of aquarium health problems. In order to determine the cause of the white dots, it's important to look at the entire aquarium environment.

  1. Ich

    • The worst case scenario when white spots are on an aquarium filter is that the aquarium is infested with ich. Ich is a marine protozoan that can kill fish. If the white spots are on the fins and body of your goldfish, they have ich. Treat your tank with an ich treatment, which can be purchased at pet and pond stores.

    Mold

    • If the white spots are thick and hairy, they may be mold. Mold frequently grows in damp areas and is common on goldfish filters. Mold, however, can pose a hazard to fish and is frequently caused by high nitrite levels. Treat the tank with a nitrite reducer and clean the filters to remove all mold.

    Mineral Deposits

    • If the white spots are crusty, they may be mineral deposits. Various minerals accumulate along aquarium walls and filters and are typically harmless. Often, these deposits can even be a sign of a healthy ecosystem developing in the tank. They may also be caused by hard water that leaves lime residue.

    Algae

    • Several species of algae are small and white, and may grow on filters, tank glass, or on the undersides of tank ornaments. If the white spots are slimy and easily remove with wiping, it's probably algae. Though many fish owners see algae as a nuisance that interferes with the tank's appearance, most algae is harmless and is typically a sign of a healthy aquarium. If the algae bothers you, try getting an algae-eating fish like the chinese algae eater to keep algae under control.