Cause & Remedy for Brown Algae in a Goldfish Tank

Brown Algae Description

• Brown algae often appears in recently set up goldfish aquariums and covers aquarium glass, gravel and decorations with soft brown clumps of growth. Brown algae is easy to remove from hard surfaces in your aquarium. It will often wisp away into a brown cloud in the water when removed by hand or with an aquarium scraper.

Causes

• Brown algae, like all algae, thrives in aquariums with excess nutrients. Brown algae is the first type of algae to appear in many goldfish tanks and remains in goldfish aquariums due to its ability to out-compete green algae and thrive in low light conditions. The algae utilizes silicates from aquarium glass as well as excess nutrients from overfeeding and stagnant water conditions to reproduce and populate goldfish aquariums.

Husbandry Remedies

• Reduce the volume of food that you feed your goldfish to ensure that there is no excess organic material accumulating in the substrate. Feed your goldfish small volumes of food several times each day rather than a large volume all at once. Carefully observe your goldfish as they feed to ensure that there are no traces of food drifting down to the bottom of the aquarium.

Environmental Remedies

• Increase the frequency of water changes when adjusting your feeding regimen to reduce the volume of organic material in the water. Use a gravel cleaner and siphon to thoroughly clean the gravel when conducting water changes in order to remove any organic debris in the bottom of the tank. Replace the light bulbs over your goldfish aquarium to ensure that the light level is sufficient, creating a less favorable environment for brown algae to grow.