Orange Algae in Fish Tank | Is It Good for Your Fish?

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Orange Algae in Fish Tank

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A small overgrowth of orange algae in your fish tank is unsightly, but it might not necessarily be bad for your aquarium.

Orange algae are mainly found in saltwater fish tanks, seashores, and other such environments, although they can also occur in freshwater fish tanks.

But is orange algae bad for your fish, and what can fish keepers do to prevent and get rid of it?

Read this guide to find out!

Can Orange Algae Be Good For Your Fish Tank?

Although an overgrowth of orange algae in your fish tank might appear unsightly, the appearance of that rust-colored growth might not be such a bad thing. In fact, many people rather like the look of the algae in the aquatic environment.

In addition, algae act rather like any other plant species, using sunlight to facilitate their respiration process, taking in carbon dioxide and releasing oxygen into the water.

That oxygen helps to maintain a stable pH level within the tank and oxygenates the water.

Is Orange Algae Toxic?

Orange algae aren’t toxic to your fish or livestock in themselves, although too much of it in your aquarium can be detrimental.

Can Orange Algae Be Harmful To Your Aquarium?

In essence, orange algae are not detrimental to the water quality in any environment, whether in a fish tank or the natural environment.

That said, the uncontrolled spread of algae can cause mortality in fish tanks.

How so?

Rising pH Levels

If algae are deprived of oxygen or any form of artificial light, they will mimic the respiration process of the animals in your aquarium.

That causes the pH levels in the tank to rise, creating acidic water conditions in which the fish will fail to thrive.


Like any living organism, algae die. As the algae die off, they begin to decompose, using oxygen in the fish tank and polluting the water with harmful ammonia.

Ammonia is extremely harmful to fish, and if levels are allowed to rise, you will experience mass fish kills.

Water Filter Damage

Your aquarium’s filter system is there to remove ammonia and nitrites from the water, keeping the environment safe for your fish and other livestock.

To do that, the filter media provides a home for beneficial bacteria that form large colonies, which process the ammonia and nitrites into less harmful nitrates.

When algae are present in large numbers, they can clog the water filter, preventing the free flow of water through the filter media and compromising the beneficial bacteria’s food supply.

Aesthetic Damage

Too much algae in your aquarium can make the water appears discolored and cloudy, ruining the aesthetics of your setup and obscuring your view of your fish.

That means more time-consuming work and hassle for you to return your tank to its former glory.

How To Prevent Orange Algae From Colonizing Your Fish Tank

So, how can fish keepers prevent orange algae from growing in the tank?

Before we discuss how to prevent orange algae from colonizing your aquarium, you need to understand the organism’s life cycle inside the tank.

What Do Orange Algae Need To Survive?

Like all other plant species, algae need light to breed and survive in any environment.

These simple organisms also need nutrients, including phosphate, calcium, and nitrates, to proliferate and grow. All these items are present in a normal, healthy fish tank.

However, you can take steps to reduce levels of those nutrients and cut down the amount of light available for the algae.

Reduce Light

Algae will happily use natural sunlight, LED lights, and fluorescent light. So, you need to relocate your tank to a spot where it doesn’t receive any direct sunlight.

If your tank is too big to move, take steps to cut off the light with shades or drapes.

Regarding marine and tropical fish tank lighting, LED lights cause algae to breed more rapidly.

Unfortunately, thanks to their low price and longevity, LED lighting units are typically the first choice for many hobbyists.

So, if you want to control orange algae in your tank, you should reduce the lighting duration in your aquarium.

Living plants need between 8 and 10 hours of light per day for photosynthesis.

If you can reduce the lighting in your fish tank to a minimum of 8 hours, the algae won’t grow as vigorously, and those levels will be sufficient for your plants.

Reduce Nutrients

Too many nutrients in the tank will enable orange algae to proliferate and spread.

Those nutrients come from four primary sources:

  • Decomposing organic matter, i.e., the bodies of dead fish and invertebrates
  • Leftover, mineral-rich fish food
  • Live rock and corals in marine tanks
  • Phosphate-rich tap water

So, start by ensuring that you remove any dead fish and inverts from the tank as soon as you spot them.

Make it a part of your maintenance routine to do a headcount of your livestock. If any of your stock is missing, check around plant bases, under decorations, and in rock crevices.

Secondly, ensure that you don’t overfeed your fish. Overfeeding is a primary cause of leftover foods accumulating in the aquarium and is easily avoided.

Basically, you should offer your fish only what they will eat in a couple of minutes, feeding them twice a day.

Again, when cleaning your tank, use an aquarium vacuum cleaner to remove any uneaten food immediately.

Partial Water Changes

Carrying out weekly partial water changes will help to keep the tank clear of accumulated nutrients, e.g., calcium, nitrates, and phosphates, removing the algae’s food source and helping to prevent its growth.

Finally, when using tap water to top off your fish tank, avoid using it if it’s very rich in phosphate and magnesium.

Test The Aquarium Water

As part of your aquarium maintenance routine, we recommend you test your aquarium water weekly. You should ensure that the levels of ammonia and nitrites are zero and that nitrates are below 30ppm.

Add More Plants

If you have a freshwater fish tank, adding more living plants can help to deprive the orange algae of the nutrients it needs since plants use the same basic substances as fertilizers.

That approach effectively starves the algae and can prevent it from spreading and growing.

Add Algae Eaters

Some aquarium fish, snails, and shrimp are known to eat algae, helping to clear the aquarium of existing populations and preventing the plants from growing back.

So, by adding a few algae eaters to your setup, you can take positive steps to eliminate algae.

Use Chemicals

You can use chemicals such as copper sulfate and other well-known algaecides to kill existing algae and prevent its regrowth.

However, you must only use these chemicals in moderation because anything that can kill algae can also harm your fish and invertebrates.

Changing The Water Flow

Adjusting the water flow by decreasing or increasing it can help to retard the growth of orange algae.

How Do I Get Rid Of Orange Algae In My Tank?

Orange Algae in Fish Tank

Orange algae overgrow and can quickly affect the health and look of your fish tank.

Here’s how to eliminate orange algae from your aquarium.

What You’ll Need

  • Aquarium net
  • Light timer
  • Glass scraper
  • Gravel filter or vacuum

Unfortunately, poor husbandry can majorly cause algae growth in an aquarium.

So, to prevent orange algae from overtaking your tank, ensure that you provide your tank with the best care and carry out routine weekly cleaning and filter maintenance tasks.

How To Do It

Here’s how to eliminate orange algae from a newly established fish tank.

Step 1 – Reduce Light

As mentioned above, algae need plenty of light to thrive and grow. So, change the light cycle in your fish tank.

If possible, move the tank to where it’s out of direct sunlight.

Keep the tank lights turned off for 12 hours per day, and consider using an automatic timer to ensure that the lights come on and off at the same time each day.

Step 2 – Don’t Overfeed Your Fish

Algae grow in response to the presence of organic matter in the tank.

Feed your fish only what they will clear in a couple of minutes twice daily. Remove any uneaten food with an aquarium net.

Step 3 – Clean Water Filters

Remove the filter unit from your tank and give it a good clean.

If any algae are growing on the filter housing or in the filter media inside the unit, they will continue to spread and grow in your aquarium.

You should also replace the filter cartridge or media to eliminate any tiny algae plants.

Step 4 – Add A Gravel Filter

Orange algae can grow on fragments of gravel in the substrate, so you need to eliminate any algae particles lingering there.

To do that, add a gravel filter or a vacuum to the aquarium to ensure the gravel is clean.

Step 5 – Wait One Week

Wait for one week.

In a new setup, it’s common for orange algae to appear after about six weeks. However, following the steps above, the algae might eventually clear up without further intervention.

Removing Orange Algae In An Established Aquarium

Unfortunately, orange algae can sometimes appear in a mature, established fish tank.

The algae get into your tank with plants, and even in the water that new fish come in fish. So, avoid emptying the water as well as the fish into your aquarium and transfer your new fishy friends with a net.

Step 1 – Clean The Glass

Clean any algae from the viewing panes with an algae scraper. That can reduce the chances of orange algae from becoming established in your aquarium.

Step 2 – Add Algae Eaters To Your Tank

If you have a freshwater aquarium with a community of peaceful fish, adding an algae eater to the setup can be a practical, attractive, chemical-free way of reducing algae in the tank.

Aquarium fish that will feed on excessive orange algae include Plecos, Siamese Algae Eaters, Red-Tailed Sharks, and most species of snails. All these creatures are readily available in pet stores and will also eat organic matter, helping reduce pollutants and keep the tank clean and tidy.

Step 3 – Use Chemical Algae Treatment

If all else fails, you can treat your fish tank with chemicals that are effective at killing algae.

First, you’ll need to remove the tank and clean all the surfaces. Once you’ve refilled the tank, use a chemical algae remover to kill off any residual algae plants and prevent future growth

Final Thoughts

I hope you enjoyed our guide to orange algae in your fish tank and how to deal with the problem. If you did, please take a few moments to share the article.

Although orange algae aren’t directly harmful to your fish, they can take over your aquarium, leaving it looking dirty and staining the fish tank water a rusty color.

You can help to prevent the breeding of orange algae by adjusting your fish tank lights so that they are off for at least 12 hours per day.

Reduce the nutrients available to the algae by keeping the tank scrupulously clean and keeping living plants. Algae eaters can also be effective at controlling algae.

How did you deal with the problem of orange algae in your aquarium? Share your tips with other readers in the comments box below.

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