How To Get Rid Of Green Algae In Aquarium

Everyone wants a beautiful clear aquarium. With an aquarium, there are some things that occur naturally which we can’t control. One of the element is algae- green algae in particular. Green algae can cause a lot of damages to an aquarium if left unchecked.  It can clog up the filter, make the water cloudy, and covers the entire aquarium with the unsightly algae. So what can be done to stop green algae?  In this article, I’ll be showing you how to get rid of green algae in the aquarium.

What Causes Green Algae In Aquarium?

Green algae are usually caused by two elements: waste and excessive lights.  These two elements combined contribute to the growth of green algae in an aquarium.

Fish waste and uneaten fish food contribute to green algae forming in the aquarium. When the waste from the fish is not removed by the filter, it gets dissolved into the aquarium water. The same goes for fish food. When there is leftover fish food, it will usually sink to the bottom and after a while, it will start to dissolve into the water.

Another element that causes green algae is excessive lights. This is usually from direct sunlight or from the aquarium lighting. Having a fish tank near the window with sunlight directly at the aquarium will cause green algae to form.

By combining dissolved waste and excessive lights together, this causes green algae in the aquarium.

Why It’s Important To Remove Green Algae From The Aquarium

Too much green algae can be bad for a lot of things in the aquarium.  It can clog up the filtration system, destroy aquatic plants, and even kill the fish!

For the filtration system, it needs to be in good working condition to remove waste and other debris from the aquarium water.  If green algae are present, it will clog up the filter screen, which prevents water from flowing.  In addition, the filter’s motor will also get clogged and that will impact the motor’s performance.  If left untreated, the motor will eventually get clogged to the point where it will stop turning.

Most aquatic plants are able to survive and live with green algae in the aquarium.  However, when there are too many green algae present in the water, that’s when the plants start to have an issue.  Plants need oxygen to live and grow.  If there are too many green algae, it will rob the plants of oxygen in the water.  Also, if it covers the entire plant, it can cause the plants to stop growing.

Another reason to remove green algae from the aquarium is that it can kill the fish.  Green algae don’t kill the fish directly, but it does so reducing the oxygen level in the water.  Fish need plenty of oxygen to live and without oxygen, they will start to get ill, and eventually die.  If left unchecked, green algae will spread quickly and can cover the entire aquarium within a couple of days.  The more green algae is present, the less oxygen will be in the water for the fish to breath.

How To Get Rid Of Green Algae From Aquarium Decoration

Aquarium decoration is what makes the aquarium beautiful and provides the fish a place to hide.  If there are green algae growing on them, it causes be unsightly and provide no place for the fish to hide.

To get rid of green algae from the aquarium decorations, you can either buy algae-eating fish, use algae solution, or remove the decorations from the aquarium and wash them.

How To Remove Green Algae On Aquarium Glass

The easiest and most effective way to remove green algae from the aquarium glass is with an algae scrubber.  What these scrubbers do is simply remove the green algae from the glass.  In order to perform this duty, you’ll need to remove the water from the aquarium to remove the algae with the scrubber.  However, if there is a small number of green algae on the glass, you can gently scrub the green algae out.  Sometimes, the green algae can be stubborn to remove, which in this case, uses a razor blade to remove it.

Another option that doesn’t require any effort from you would be to add some algae eater to the aquarium.  The best algae eater are the plecostomus, loaches, cory catfish, snails, and shrimps.  These marine creatures are great for helping remove green algae from the aquarium glass and preventing green algae from spreading all over the glass.

How To Prevent Green Algae Growth

Getting rid of green algae naturally is easier than you think.  Remember that green algae need food and lights to grow.  By eliminating these two elements, you can stop green algae from growing in the aquarium.

For aquarium lighting, try to reduce as much lighting as possible.  During the day, turn off the aquarium lights.  In the evening, turn the lights on and you can leave it on until the morning.  By reducing the number of lights coming from the aquarium lighting, you’ll reduce the chances for the green algae to grow.

If your aquarium is located close or by a window, you can reduce the amount of direct sunlight by pulling down the window shades.  Another option would be to use a tinted film and cover the windows during the daytime hours when the sunlight is strong.

As for the waste from the fish, you’ll need to install a good filtering system.  Depending on the size of your aquarium and how much fish is in the aquarium, you’ll need to get the right size filter to filter out all the waste.  There is a couple of good filtration system on the market.   For aquarium up to 200 gallons, I personally recommend Tetra Whisper Filter System from Amazon.  I have it in my aquarium for the past 3 years without any trouble (as long as you follow their maintenance schedule).  As long as the waste doesn’t stay in the aquarium for a long time, it will have fewer chances to dissolve into the aquarium water.

Food is another element that contributes to the green algae in an aquarium.  Left over food will likely sink to the bottom of the aquarium and dissolve into the water.  To prevent this from happening, feed the fish with just the right amount of fish food at a time.  If they are still hungry, you can give them more, but no more than they can eat without the food sinking to the floor.

What Freshwater Fish Eats Green Algae?

To keep green algae from spreading out of control, there is a certain type of freshwater fish you can keep in the tank. These fish will help keep the aquarium free of green algae.


Plecostomus are good algae eating fish for any size aquarium. They are bottom-feeders that have a large sucker-mouth that can cover a lot of ground, which means they can consume a lot of algae in a short period of time.

The biggest benefit of having plecostomus in your aquarium is their ability to consume not just green algae, but other types of algae as well.  The Green Spot Algae is one of them that other algae eating fish will not eat.

With this fish, no matter how large your tank is, Plecotomus is the right choice to keep green algae and any other types of algae from spreading out of control.


These tropical fish are not algae eater, but they are known to eat green algae and other types of algae in the aquarium.  Mollies are not a picky eater and will eat just about anything that is given to them.  Mollies will feed on green algae from the plants, substrates, and even from the aquarium glass.

Having mollies in the aquarium can help reduce or prevent green algae from inhibiting the aquarium.


These tropical fish are a bottom feeder and will do a great job of keeping the aquarium substrate free of green algae.  Not only will they keep the aquarium floor clean of green algae, but it will also keep the plants and decorations clean as well.

Loaches are great to have in any aquarium as they get along well with other fish, especially other bottom feeders.  By having a couple of loaches and other bottom feeder fish in the aquarium, you are sure to have your aquarium free of green algae.

Cory Catfish

These tropical fish are small and love to eat green algae.  They can get into small places that other bottom feeder fish can’t get to.  They are especially useful if you have an aquarium with a lot of decorations.  Aquarium decorations tend to have a lot of small crevices and holes, which a lot of fish can’t get to.

Cory catfish will mostly eat things on the aquarium floor, and not above it.  For that reason, it’s a good idea to have other algae eater in the aquarium along with Cory catfish.


Green algae are good for the aquarium as it provides food for some marine creatures to feast on.  It becomes a problem when there are too many green algae present in the aquarium water.  Getting rid of green algae in the aquarium can be a daunting task, but it doesn’t have to be if you know how to get rid of it properly.

To prevent yourself from having to clean green algae from the aquarium often, use preventative maintenance and you won’t need to worry about green algae for awhile.

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