What Are the Causes of Algae in a Fish Aquarium?

There are three things needed for algae to grow in a fish aquarium: water, light and nutrients. Since all three are also vital to the fish, you can't eliminate them, but there are steps you can take to help minimize algae growth.
    • Clean aquariums help keep fish healthy.

    Water

    • When algae growth appears, make an initial 20-percent water change for five to seven days until the water is clear again. Once the algae is gone, continue to make a 20-percent water change twice a week to help prevent growth from recurring.

    Light

    • If you're using a hooded light, place the light on a timer and minimize the amount of time the light is on. If your aquarium is in a sunny spot, move it away from direct sunlight or place something over the side of the aquarium receiving the most light.

    Nutrients

    • When fish eat, they produce waste in their water, which produces nutrients for algae. So it is important to not overfeed the fish. Also, be sure to remove any dead fish from the water, since the decay is not only unhealthy for the other fish, but adds more nutrients for the algae.

    Algae-Eating Fish

    • There are several fish that eat algae such as Siamese Algae Eaters and Plecostomus Catfish (Pleco) that can be helpful in eating some types of algae. It is important to realize, however, that the Pleco can become very large and the 3-inch fish you brought home for your aquarium may eventually become more than 12 inches long.

    Chemicals

    • There are several chemicals on the market that will help with removal, but it is best to keep the aquarium as natural as possible. Water changes, light control and keeping the aquarium clean are the best defense in keeping algae from returning.