What Are the Characteristics of Algae?

Fish tanks can suffer from algae-related problems when there are excess nutrients, fish waste or unhealthy water conditions. Different variants of algae have their own unique characteristics. Many types of algae flourish with constant harsh lighting and grow rapidly toward a light source. Others, such as brown algae, prefer dark conditions and grow flat and dense, spreading across surfaces.

  1. Brown Algae Diatoms

    • Soft brown algae occurs in new tanks before water stabilization has been achieved or when there is insufficient light. It is caused by diatom organisms and appears on glass in the form of a fluffy residue. Wipe away the algal growth from glass with a cloth or gently scrub tank ornaments to remove deposits.

    Cyanobacteria

    • Cyanobacteria is a blue-green slime that quickly grows out of control in poor-quality water. It is a persistent type of aquarium algae and difficult to remove because of a slippery consistency and strong adhesion to plants, gravel and rocks. An algaecide containing erythromycin phosphate treats cyanobacteria, but side effects include high levels of ammonia and nitrates, so use an aquatic test kit to monitor water chemistry during treatment.

    Beard Algae

    • A bright green fuzz on aquarium plant leaves is the first sign of beard algae. The algae develop into compact bushy growths that are very difficult to remove without damaging plants. A commercial broad-spectrum anti-algae treatment suppresses beard algae and prevents recurring outbreaks.

    Spot Algae

    • Small, hardened discs of algae on aquarium glass are spot algae, caused by excess light in a fish tank. Spot algae are flat and crisp in texture, and scrubbing with an abrasive tool removes the residue on glass aquariums. Rub down acrylic tanks with a soft cloth to avoid damage and surface scratches.

    Thread Algae

    • Excess iron is the cause of thread algae in fish tanks. Aquarium plant food contains a form of iron that dissipates into the water quickly, but overfeeding plants results in too much residual iron and promotes the growth of thread algae. It is characterized by deep green strands, up to a foot in length, gravitating toward a light source. Thread algae grows on filters, glass, ornaments and flat surfaces. Scrape away the base of the algal bloom as soon as it appears, and carry out regular partial water changes to maintain healthy water.

    Staghorn Algae

    • Individual strands of matter resembling the formation of deer antlers are staghorn algae. These are grayish green and float freely in the water or latch onto surfaces. Anti-algae solutions effectively treat staghorn algae, but you can also scrub affected areas and pull out the residue by hand.

    Hair Algae

    • Rough clumps of green growths around 2 inches long are hair algae. They typically appear on filters and plants before spreading to gravel and rocks. Once the spores embed into the substrate, it becomes very difficult to remove hair algae manually. Reduce light levels and treat your aquarium with an algaecide to control hair algae.

    Brush Algae

    • Brush algae is initially noticeable on plants with large flat leaves before it spreads to the rest of the aquarium. These soft, black fluffy growths are also known as audouinella. Algae-eating fish can keep a small outbreak of brush algae under control, but a commercial copper treatment will eradicate the problem.