How To Remove Staghorn Algae In Aquariums

How To Remove Staghorn Algae In Aquariums

Compsopogon sp. (also known in the aquarium hobby as Staghorn algae) is a freshwater red alga of the family Compsopogonaceae. In nature, these algae are widely distributed throughout the world, but is most common in tropical and subtropical regions and occasionally extends into north temperate regions such as northern states of North America, Europe, Japan, India, and Brazil.

Whether you’re a new aquarium owner or a seasoned one, you’ve no doubt heard about the different types of algae that can grow in your planted tank. Even though Staghorn algae are probably the ugliest of all the algae that we can get in our tanks, this is not the main downside.

The main problem is these algae are a total mystery for me. In some cases, it can be very easy to get rid of, while in others, it seems like nothing works and helps against Staghorn algae.

There are also a lot of debates about these algae. Therefore, in this detailed guide, I have gathered all information about Staghorn algae and how to remove it in aquariums based on existing studies, experiments, researches, and experience of aquarists. 

What Are Staghorn Algae?

How To Remove Staghorn Algae In AquariumsSo, what exactly are Staghorn algae? The genus Compsopogon (Staghorn algae) includes a few described species of filamentous algae, which are distinguished in general by their characteristic bluish, grayish or violet-green color.

It is quite interesting but the color of the algae should not confuse you. Staghorn algae belong to the group of red algae. Once it starts dying it will turn red.

Most aquarists will easily recognize it growing within their tank even before it is fully formed.

Easily identifiable as a stringy, vein-like mass of dark gray clumps – usually found growing over aquarium plants – this branching growth got its name from the antler-like shape such clumps take on. They are primarily found on the edges of slow-growing plants.

Once Staghorn algae growth accelerates, it can eventually cover your aquarium surfaces completely, ruining the aesthetics of your tank and compromising the health of its inhabitants. Should it grow thick enough, the algae could block light from the aquarium plants underneath it, and even steal away nutrients.

Causes of Staghorn Algae

How To Remove Staghorn Algae In AquariumsIf you have discovered some clumps of Staghorn algae in your tank – or are searching for preventative measures – you may be wondering what causes it in the first place. As with most troublesome life forms, there are a variety of potential factors that may lead to an algae invasion.

Lots of articles, forums, and Facebook groups list the following the most common causes of Staghorn algae:

Poor CO2 Levels

An undersupply of CO2 is not just detrimental to the health of your plants, but it can also lead to Staghorn algae. As one of the largest causes for growth, it is important to regularly check for leaks or blockages in your aquarium’s CO2 system, and ensure you’re using the appropriate amount.

Note: If low CO2 levels were the cause of Staghorn algae then every low tech tank should have it. Therefore, I do not think that low CO2 can be the main reason. However, fluctuations in CO2 will favor algae growth.

Inefficient Light Supply

Everything is better in moderation – even when it comes to aquariums. To keep a Staghorn algae bloom for terrorizing your plants, place a limit on how long you keep your aquarium light powered.

Too much light can lead to a perfect environment for algae growth – something easily preventable with a timed device. Keep in mind, this doesn’t mean keeping your light off indefinitely – too little light can damage the growth of your plants as well.  

Note: Unbalanced lighting setup can cause many more algae as well.

Inadequate Water Circulation

Even if you are keeping up with everything mentioned above, a poor amount of water circulation can be another recipe for Staghorn algae.

Without proper water flow, CO2 – and other essential nutrients for that matter – won’t disperse properly throughout your aquarium, leading to malnourished dead zones that make perfect Staghorn algae breeding grounds.

Note: This one a ‘like’ the most. According to one of the studies, the alga grew most lavishly where the water current was highest. Other biologists also reported that this red alga appears mainly in streams. The species seemed unable to initiate successful colonization in slow current or standing-water conditions. However, it could tolerate such conditions for relatively long periods.

In my opinion, in aquariums, inadequate water circulation has another role. It simply prevents nutrients from spreading to every corner of the tank.

Low Nutrient

According to the study, freshwater red algae were reported to only appear in high oxygen concentrations and the low nutrient aquatic environment.

Many aquarists also reported that Staghorn algae appeared from ammonia even if its level was too low to measure.

Personally, I believe that low nutrients in the main cause of Staghorn algae. It also perfectly correlates with bad water circulation.

Low nutrients mean that the plants cannot get enough resources to grow and compete with the algae. You may have zero readings and still develop Staghorn algae. In fact, zero readings are worse for plants and better for the algae.

Therefore, when we add to this equation light and CO2 imbalance the chances of getting algae increase proportionally.

Are Staghorn Algae Harmful to Fish or Shrimp?

If you’ve supplied your aquarium with inhabitants other than plants, you’ll likely be concerned about the effects Staghorn algae can have on the health of your fishy roommates. Thankfully, it hasn’t been proven to harm fish or shrimp – although they may be irritated in having to share tank-space with this bristly ‘stranger’.

Still, you will want to keep in mind that plants play an essential part in the lives of your fish or shrimp. Not only do they provide a more natural environment for your pets, but also work to improve water quality – therefore making your fish stress-free and happy.

So, while Staghorn algae might not directly affect fish or shrimp, they can still inadvertently affect them through the damage caused to aquarium plants.

Are Staghorn Algae Harmful to Plants?

How To Remove Staghorn Algae In AquariumsAs we have already mentioned, algae growth can pose a slew of problems when it comes to the health of your aquarium plants, which is what makes understanding how to remove staghorn algae so vital to your tank’s wellbeing.

Staghorn algae are great at stealing from your plants. First, clumps can force plants to compete with it for resources as it grows in size, potentially denying your plants a portion of much-needed nutrients necessary for proper development and health maintenance.

Additionally, Staghorn algae are primarily found growing along the edges of plants: once it has reached a greater thickness, it will prevent light from reaching the plants underneath it, blocking yet another essential nutrient from your tank’s ecosystem.

As a side note, a majority of causes behind Staghorn algae means bad news for your plants: low CO2 levels, insufficient water circulation, low nutrition, and an overabundance of light to be mentioned.

If any of these reasons are growing algae in your aquarium, it suggests your plants are already being harmed. Knock out two birds with one stone by focusing on keeping your plants healthy – that way, Staghorn algae will find it harder to find a place to grow.

Methods of Eliminating Staghorn Algae

It’s a day you didn’t expect, or maybe even one you’ve been dreading: the day you find your aquarium invaded with Staghorn algae.

After reading through the article, (because you did, right?), you easily recognize it from its dark grey, branch-like appearance, and a location near or on your aquarium plants.

Perhaps you’ve forgotten to properly time the amount of light you leave on your tank, accidentally injected too little CO2, etc. – do not worry, there is no need to panic. Everybody makes mistakes!

Allow yourself a moment to recover, and then get to work. There are plenty of methods we know for how to remove staghorn algae.

Manual Removal and Water change

  • Try to manually remove all of the Staghorn
  • Trim the plants even further if you have to.
  • Be careful, do not tear the algae apart, do not let it float in the tank.
  • Clean the filter and substrate vac.
  • Do big water change.

If there are no serious problems in your tank, it can help you to remove Staghorn algae and take care of the problem.

Tip: Take an old toothbrush and try a twirl around the Staghorn algae to remove as much as possible.

Potential problems: Huge water changes can cause serious molting problems for the shrimp.


Reducing the photoperiod for 3 days can work excellent against Staghorn algae.

How to do a Blackout:

  1. If you have fish, feed them a regular amount of food. Do not overfeed. If it is a shrimp tank, you may even skip this step.
  2. Turn off the CO2 (if you run one).
  3. Do not add fertilizers during the blackout.
  4. Increase the oxygen supply. Install a new air-pump if needed.
  5. Cover the tank with a thick blanket. It must be completely dark in the tank.
  6. Leave the tank this way for at least 3 days.
  7. Open up half of the tank and leave like this for 30 minutes. Let your fish adapt.
  8. Remove the blanket completely and wait another 30 minutes before switching the aquarium light on.
  9. Clean equipment as the dead Staghorn can clog it easily.
  10. Trim off all the dead leaves or ones that had algae.
  11. Do a water change. If it is a fish tank, it can be 50% water change. If it is a shrimp tank – 10% water change.
  12. Change your light timer to 6 – 8 hours for the next week.

Potential problems: It can harm plants that require a lot of light but they should survive.

CO2 Spot Treatments

Using a CO2  solution doesn’t only assist growth for plants in your aquarium, but also aids in ridding it of these algae. By adding it to a tank, you should see Staghorn algae begin to die within several days.

If that doesn’t work – or you want a quicker process – you can directly apply the solution onto algae clumps with a syringe or pipette daily.

Note: Adding enough CO2 (which is also an acid) causes algae to go away.

CO2 Balance

If you are running CO2 systems, check it if it is too low. There is a chance that CO2 and light are not balanced.

Therefore, increase CO2 to 10 – 25 % and decrease light to 10 – 25 % of normal output for a week to see some changes.
Note: We use CO2 mainly to help our plants. Stable CO2 favors plant growth. It makes them stronger so they can outcompete Staghorn algae.

Therefore, if your tank is out of balance CO2 (for example, when we have swings in CO2 when we are trying to find the right amount that will work for the tank), it can make things even worse.

Hydrogen Peroxide and Spot Treatment

shrimp tank Hydrogen PeroxideHydrogen peroxide is an efficient way to battle Staghorn algae if you do not want to use the CO2 method. Using what is called the “fogging method”.

  1. Turn the filter off!
    Note: We do that so that beneficial bacteria will not be affected.
  2. Turn the air pump off.
    Note: We do that to have very little to no water movement. It will let the hydrogen peroxide to be around the algae longer.
  3. Turn the lights off.

Note: The decomposition of H2O2 happens much faster in the presence of light.

  1. Fill a syringe with 3% Hydrogen peroxide, (3ml for every 1 gallon or 4 liters),
  2. Apply it directly onto algae clumps.
  3. You will see lots of bubbles. It is OK. The Staghorn algae are serving as a catalyst for the H2O2, releasing only O2 and leaving behind some hydrogen in the process.
  4. Avoid hitting any plants, shrimp, or fish in the process! Most fish and shrimp are pretty curious and can come to the treatment zone and see what is happening! It will harm them!
  5. Next, in a few hours, manually remove dying algae (it will turn reddish).
  6. Turn the filter on.
  7. Next day, do your weekly water change.

Potential problems: Overdose Hydrogen peroxide will harm the shrimp and fish. Their gills are very sensitive. Some plants like Mosses, Vallisneria, Bucephalandra, etc. can melt. Many other plant species respond well.

Hydrogen peroxide – check out the price on Amazon

Hydrogen Peroxide and Spot Treatment. Alternative way

  1. Do a huge water change.
  2. While the tank is drained and plants exposed, spray H202 directly on affected plants.
  3. Wait 5 minutes.
  4. Refill tank.

Potential problems: I do NOT recommend to drain the tank if you have shrimp. They will die. The concentration of this treatment will be simply extreme for them to handle. In addition, huge water changes can cause serious molting problems for the shrimp.

Hydrogen Peroxide and Full Tank Treatment

If there are too much Staghorn algae, you can try to use full tank treatment. However, BE VERY careful. Measure the water volume of your aquarium. Take into consideration even substrate, decorations, etc.

  1. Turn off your filter.
    Note: Ideally, you need to remove filter media so that beneficial bacteria will not be affected. In this case, you can keep the filter running for additional water flow. Unlike Spot treatment, it is a more serious threat to the bacteria.
  2. Increase aeration. When the algae start to die off, they will begin to decompose. This process will absorb lots of oxygen. Depending on the situation, it can even suffocate your fish or shrimp.
  3. Turn the lights off. (it will improve the treatment efficiency).
  4. Use 3% Hydrogen peroxide at 1.5ml per gallon or per 4.5 liters.
  5. Evenly spread H2O2 across the surface of the aquarium.
  6. Gently stir the water to spread it.
  7. Wait 1 hour.
  8. Turn the filter on or put the filter media back.
  9. The same week do a water change and add your favorite bacterial supplement back to the tank.

Potential problems: You may lose some beneficial bacteria that attaches itself to any surfaces throughout the aquarium, it is on the décor, live or fake plants, driftwood, rocks, tubes, heaters, glass, substrate, etc. That is why it is important to add bacterial supplements back to the tank.

Seachem Flourish Excel and Full Tank Treatment

Seachem Excel vs algaeSeachem Flourish Excel is based on Glutaraldehyde (C5H8O2), and it works perfectly against any type of algae (including Staghorn algae).

Alternatively, you can try spot dosing (use the same technic as with Hydrogen peroxide). This involves using a pipette or syringe to apply Seachem Excel directly to the Staghorn algae.

  1. The is not just to dose it but to heavily overdose!
  2. Day 1 – use a standard dose of Flourish Excel.
  3. Day 2, 3, and 4 – use a double or triple dose.

In a day or two, you should notice that Staghorn algae turn reddish. It means that it is dying. After some time, it becomes white and begins falling off.

Tip: Dose in the evenings, toward lights out, it will increase the efficiency.
Note: If you have Staghorn only in several places, it can be better to use a syringe and treat these places individually instead of treating the whole tank.

Potential problems: You have to understand the danger and take responsibility!
If you do it, you do it at your own risk!

  • Overdosing can be lethal to your fish and shrimp.
  • Some plant species may melt away and die. For example, be careful with sensitive plant species like mosses, Val’s, etc.
Seachem Excel – check out the price on Amazon

Seachem Flourish Excel + H2O2 vs Staghorn Algae

If for some reason, Staghorn algae are too resistant you can use a combination of both methods – a 50/50 mixture of 3% Hydrogen peroxide and Seachem Flourish Excel.


Easy Life EASYCARBO vs algaeThis is another product that is based on Glutaraldehyde. EasyCarbo is an extremely powerful and effective carbon source for aquarium plants.

  1. Start with the recommended dose (1 ml per 50 liters or about 12 gallons daily).
  2. Increase the dosage on a weekly basis.

Potential problems: Overdosing of EasyCarbo can cause plants (like Mosses, Vallisneria) melt and death of inverts! Observe your inhabitants and perform immediate water change if you notice suspect behavior.

Easy Life EASYCARBO – check out the price on Amazon


API algaefix vs hair algaeThere are some positive reports that AlgaeFIX works like a charm and can completely eradicate Staghorn algae.

Potential problems: That product has extremely powerful chemicals. Unfortunately, it is also not safe for invertebrates including shrimp, snails, crayfish, etc.

Even more, in spite of the description that it “controls many types of algae in aquariums and will not harm your fish or plants when used as directed”. There also some complaints that AlgaeFix also killed fish, even when dosed according to the bottle.

That is why many aquarists use it for dips only and use it as a full tank treatment only in desperate situations.

AlgaeFIX – check out the price on Amazon

Razor Freshwater

Razor Freshwater vs algaeThere are also reports that Razor Freshwater from Brightwell was able to eradicate the Staghorn algae from the tank completely in a week.

Follow the recommended dosage. This product was specifically designed to target and clean surfaces of rock, driftwood decorations, and tank walls.

Potential problems: It is not shrimp safe.

Razor Freshwater – check out the price on Amazon

Who Can Eat Staghorn Algae?

Lots of people on forums ask this question. The problem is that almost nobody will eat Staghorn algae. Even the famous Amano shrimp and American flag fish do not appear to find this species very palatable. They can eat it only when it’s dying (turns pink/red).

However, in one of the studies, I found that there are two fish species reported to actively graze on this alga, most notably Sturisoma panamense (The Royal Farlowella) and Ameca splendens (Butterfly Goodeid).

Note: Personally, I cannot prove or disprove it.

Tip: Spot Treatment for any Product

  1. When you fill the syringe with the treatment, do not fill it completely. Let it be ¼ or 1/5.
  2. Fill up the rest with air.
  3. Use it to the affected areas. Important: Quickly pressed it out.
    Note: If you slowly press out the treatment, it will just dissolve and float away in the water. Thus, the efficiency will be low.
  4. It will create a ton of microbubbles. Those microbubbles will easily attach to the algae. It will increase the efficiency of the treatment.

How to Prevent Staghorn Algae in Aquarium

All things considered, you will save both time and energy in taking the proper preventative measures when it comes to Staghorn algae.

Taking great care in keeping your aquarium operating at full efficiency is no doubt the best method in keeping not just algae at bay, but also a variety of additional factors that might compromise your aquarium’s presentation.

Here are a few tips on keeping your tank clean and preventing Staghorn algae:

Use Fertilizers

Make sure your plants get the proper amount of Nutrients. Adding fertilizers while trying to clean up Staghorn algae does sound counter-intuitive at first, but this is one of the most important steps in this battle.

Unhealthy and weak plants attract algae. That is why we have to give the plants what they need to become healthy and strong. We have to find the proper balance between proper light, CO2, and nutrients. We cannot neglect any of these areas without affecting the demand for others.

Important: If you keep shrimp in the tank, I would highly recommend reading my articles:
How Copper Affects Dwarf Shrimp
Shrimp Safe Plant Fertilizers
The point is that many fertilizers contain copper that is extremely dangerous to the shrimp.

Maintain Stable CO2 Levels

By now, if you have a high-tech tank, you should recognize better than ever how vital CO2 is in properly managing your aquarium. Avoid low or fluctuating CO2 levels to keep algae growths from appearing.

Once again, we use CO2 mainly to help our plants. So that they will be able to outcompete Staghorn algae.

Improve Water Circulation

Efficient water circulation is of paramount importance in properly spreading nutrients to every corner of your aquarium and preventing dead zones – perfect breeding grounds for Staghorn algae – from forming.

Here’s a good rule of thumb to follow: if only some of your plants are swaying, you need higher water movement, as all of them should be swaying.

Use a Timed Aquarium Light

An overabundance of light can encourage an algae bloom. Combat this by using a timed aquarium light – or at least keep tabs on how long you’re using yours if you don’t have one – to keep light supply level.

You’ll want enough to keep your plants healthy, but too much will cause problems: maintenance is key!

You can also read “Advanced Guide to Planted Tank Lighting”.

Schedule Regular Maintenance

It is no question that your aquarium requires maintenance, whether it be cleaning filter pipes, maintaining crystal-clear glass walls, or getting rid of unnecessary organic wastes. By ensuring you stay on top of your tank’s needs, you will, in turn, keep an eye on factors that might lead to Staghorn algae.

Regular tank cleaning and water-changing should also be a staple in your schedule. Regardless, this is a great way to keep your aquarium’s inhabitants happy and healthy.

In Conclusion

So, if you are an aquarium owner who wishes to keep your aquarium clean and sparkly, then you have most likely already encountered more than a few of nature’s troublemakers. Cloudy water, algae, and waste can all play in a hand in turning your aquarium from a sparkling oasis into a hazard zone.

Staghorn algae don’t have to be the end of the world. Luckily, these growths don’t have any direct effects on the creatures living within your tank, but it is worth keeping an eye out all the same. Remember: they can still impact the health of your plants!

While staghorn algae may certainly prove to be an annoyance, by taking the proper preventative measures – and following the right elimination methods in case you’re struck by an algae bloom – you can save yourself the headache.

Related articles:

How to Remove Staghorn Algae in Aquariums pinterest


8 thoughts on “How To Remove Staghorn Algae In Aquariums

  1. Great article, thank you very much; I like all the research you’ve done to prepare this page.

    Question: what may be the role of temperature in triggering the growth of staghorn algae?
    I noticed that my 4 ft planted tank started to grow this alga a few weeks ago, when the water temperature increased, as we are entering into the summer season here in Australia.
    Do you have any experience with temp changes and this alga?
    Thank you! Guillermo

    1. Hi Guillermo Diaz,
      Personally, I have not had that kind of a problem.
      Nonetheless, regarding your situation, theoretically (just my guess), I think that temperature fluctuation decreased CO2 in your tank. Even though these changes were pretty small (something around 4 – 5 ppm), they could still trigger algae growth.
      Best regards,

  2. Hi Michael,

    I find your work a treasure trove of resources covering the most common and most asked about issues in fishkeeping and planted tanks. The topic of Staghorn Algae for me has been an adventure to research. So many idea and opinions. This page is by 5 fold the most comprehensive page on this topic. Many of the treatments covered are like dancing on the edge of a knife with the health of the inhabitants. A note for you: Anacharas is killed and melts away with every chemical treatment on the page.
    A topic not covered is PO4 and the role it plays in Staghorn Algae growth. Plants need PO4 and it can be found in many fertilizers. Fish food usually contains PO4 and usually has more than enough for the plants. But having both sources often brings on an overdose of PO4 and this makes Staghorn Happy!. I find that when I see Staghorn that if I use a PO4 remover like Seachem Phosguard that in 2 days the Staghorn is gone. This treatment will not harm the inhabitants or plants as it is restored by feeding the fish.
    Other fish that eat Staghorn are Siamese Algae Eaters and most Garra species. As you point out nothing will eat it if you feed them something that tastes better. Garra are fairly new to the aquarium industry and really worth adding to your cleanup crew. Especially if your planted tank has large inhabitants like mine does.

    1. Hi Ken,
      Thank you for the feedback!
      Best regards,

  3. Hi Michael,
    I am battling staghorn algae and nothing seems to be working. I have a 5 gallon planted tank and I am dosing Seachem Flourish. I lowered the light intensity and photoperiod but it did not work. Last time I checked I had 0 ppm Ammonia, Nitrite, and Nitrate. I am dosing Flourish at the recommended dosage but the Nitrate levels are still low. Should I increase the dosage? If so how much?

    Plants: Java Fern, Hygrophilia Siamensis 53b, Cabomba and Cryptocoryne Wendtti Green

    Light: 10 watts 40% intensity 8 hours 6500 K 45 PAR 420 Lumen
    Nicrew LED Plus

    Substrate: Dirted tank with Flourite Cap

    Filtration: HOB filter but with no media inside of it.

    C02: None

    Also, my Cabomba is yellowing and it has some white stringy algae. It has grown a decent amount of roots. The white stringy algae are also on the Java Fern roots. Any advice?


    1. Hi Jack,

      In my opinion, Staghorn algae are even worst than Black beard algae. It can be really hard to get rid of.
      Are you spot treating it?
      In most cases, the recommended dosage of Seachem Excel will not be strong enough. Therefore, it should be at least doubled.
      However, I need to repeat that overdosing can be very risky for some plants and animals!
      Have you tried a complete blackout?

      Best regards,

  4. Hi Micheal,
    I read that aeration can be quite beneficial for increasing oxygen and surface agitation and hence added an air stone. The air comes on 2 hrs after the co2 and switches of 2 hrs before co2 comes on. Do u think this can be an trigger for the staghorn. I do have an army or amanos and SAE in the tank, along with spot dosing excel. But now I am going to try the method with filling air and blasting with micro bubbles. Can this tecnique be used for H2o2 as well?

    1. Hi Ben Attokaran,
      Yes, surface agitation promotes oxygen saturation.
      Frankly saying, I don’t think that aeration can cause Staghorn algae. However, it is really hard to pinpoint the problem with these algae.
      Also, I keep checking for some studies that can help us with this problem. Unfortunately, there is no good news yet.
      As for your method, why not? Just be careful with Hydrogen peroxide.
      I’d really like to know the results. Please keep me posted.
      Best regards,

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