API Algaefix Algae Control Aquarium Solution

Rated 3.5263 out of 5 stars


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About This Item


  • Specially developed to help treat and control algae growth.
  • May help to reduce the amount of maintenance your aquarium requires.
  • Safe enough that it can be used weekly and will not harm your fish or plants.
  • Effectively controls ldquo green water rdquo algal blooms and string or hair algae.
  • Not for use in saltwater or with freshwater crustaceans and recommended for indoor aquarium use only.

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Play Video: Learn More About API From Our Team of Experts
Learn More About API From Our Team of Experts

Help keep your glass aquarium extra clean with API's Algae Scraper.
Help keep your acrylic aquarium extra clean with API's Algae Scraper.

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About API Water Conditioners

It’s Smart To Be Proactive!

The best way to keep your aquarium clean is to maintain good water quality. This will help keep your fish strong and vibrant and prevent disease. Water conditioners and test kits from API can help you keep your aquarium water safe and healthy.

How Do I Maintain a Healthy Environment?

It is important to test your aquarium water weekly to ensure it stays healthy for your fish.  In addition, a bi-weekly partial water change of no more than 25% will help reduce toxic buildup, remove debris the filter missed, and replenish the oxygen available to your fish.

Feed Twice Daily and Test Water Weekly

Feed your fish twice a day, check their water temperature, and observe them to make sure they are active. You should also test water quality weekly for optimal safety. For fish to thrive, their water must closely match that of their natural environment—poor water quality can cause stress, illness and even fish loss. The 6 important parameters for healthy aquarium water are ammonia, nitrite, nitrate, pH and water hardness (GH & KH). All of these can vary over time and are invisible to the eye.

Change Water and Restore the Ecosystem

In a closed aquarium environment, there are no natural rivers or streams to carry away debris and other waste materials. That is why you should replace 25% of your aquarium water every two weeks, making sure to add water conditioner to your tap water to make it safe for your fish. You should also change your filter media and clean your gravel monthly. Adding beneficial nitrifying bacteria with API Quick Start when you do will help restore your aquarium’s fragile ecosystem and avoid disruption.

What Do API Products Do and When Do I Use Them?

API Test Kits

Use test kits weekly to monitor water quality parameters, which can vary over time and impact the health of your fish.

API Stress Zyme

Using this every week will help keep your aquarium clean and your gravel and ornaments sludge-free.

API Algaefix

Use weekly to control algae growth and keep aquarium glass, ornaments and plants clean.

API Stress Coat

Use every 2 weeks during water changes to make tap water safe, and when adding fish, or when fish are injured.

About API

The team at API has a passion for fish and understands the rewards and relaxation fishkeeping can bring. For almost 60 years, they have developed premium products with a focus on proven and effective results. API offers a range of testing kits, water conditioners and nutritionally superior fish foods. They are dedicated to making a better underwater world for the benefit of fish and those who keep them.

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Fish TypeBetta, Cichlid, Goldfish, Tropical FreshwaterCichlid, Goldfish, Marine Fish...Tropical FreshwaterTropical FreshwaterBetta, Bottom Feeder, Cichlid, Discus, Goldfish, Tropical Freshwater
Aquarium TypeFreshwaterSaltwater, FreshwaterFreshwaterFreshwaterFreshwater
Top Ingredients100% Natural, novel Bacteria mixture

Questions & Answers

28 Customer Questions

Will it harm snails? Used a product years ago that killed off of my snails. So I'm very nervous about an algae killer. Says it safe for fish and plants...but what about invertebrates?
Answer by ChewyMar 13, 2018
This product cannot be used with freshwater crustaceans (snails).

Can it be used for aquatic turtles?
Answer by ChewySep 06, 2017
This can be used in a turtle habitat. Do not use in aquariums that house crustaceans such as shrimp, crabs, or lobsters.

I have a small (2 or 2-1/2 gal) tank for my Betta. How much Algaefix would I add for this tank? You say 1 ml to 10 gallons. I assume it would only be drops. Pleas advise.
Answer by ChewyJun 14, 2020
It is recommended to use 1 mL for a 10 gallon tank so you'd need approximately 0.25 mL of this solution for a 2.5 gallon tank.

If I take my snails out of the tank and use the algae fix will it be safe to put them back in after a couple days
Answer by ChewyMay 20, 2020
We’d recommend using the API ALGAEFIX MARINE aquarium algaecide, which will not harm marine fish, corals, or invertebrates (snails).

ReviewsWrite a Review

Rated 3.5263 out of 5 stars
76 Ratings
Would recommend to a friend

75 Customer Reviews

Rated 2 out of 5 stars
By Timothy on Nov 10, 2023

It says itit'safe for all fish.. My fish in my 20 gallon seemed traumatized for days. But, my betta, in a 5 gal. didn't eat for 5 days. Layer around, basically dying, until changed all the water. Luckily, he came back. NOT KEWL

Rated 1 out of 5 stars
By Jenell on Sep 9, 2023

IM A SCIENTIST! And this is awful.

I figured people were more often than not messing up their dosage which is why their fish were dying but alas my happiest fish is now dead. Now I only have grumpy gus and powder who always looks sort of dead and I STILL HAVE ALGAE! I just cleaned my tank as well five or so days before so it was prime time to use an algae fixer. Obviously, I would not buy this again nor suggest others to use it unless you hate your fish.

Rated 1 out of 5 stars
By Erin on Oct 31, 2023


This stuff will kill your whole tank in a single dose in a single night - you will be lucky if any survive. DO NOT BUY

Rated 3 out of 5 stars
By Ang on May 5, 2023


Make sure you read directions carefully. It says to use 1ml per 10 gallons. Now the cap is a measuring cup and has two measurements 5ml and 10ml. For some reason I thought it was 1ml and 2ml. I have a 20 gallon tank so I needed 2ml for my tank so I filled the cap to the brim and dumped it in.. later realizing that the measuring line at the top was 10ml not 2ml so half of my fish died 20 dead so far. And it didn't even clear the water. It only took the green algae away it's still cloudy

Rated 1 out of 5 stars
By Steve on Dec 31, 2022

Fish Poisoned

It’s not often that I take the time to review the item, but I am completely disappointed in this product. The bottle states that neither the fish nor aquatic plants will be harmed, this is simply not true. I followed the instructions for my 20 gallon tank, and woke up to find all six of my Corydoras dead and a number of Guppies alongside them. The algae has not been impacted and I will certainly not be dosing the tank again.

Rated 1 out of 5 stars
By kit on May 30, 2023

Please do not use....killed my fish!

Rated 2 out of 5 stars
By KimR on Aug 23, 2022

Worked great but harmed my fish

Worked great and the water was clear again but my fish stopped eating! I did some research and found if you use it as directed it can kill your fish even though it claims to be safe. I ended up having to do a 50% water change. I read using a smaller amount is better so I used a 1/4 of the directed amount and not only did it not work but the fish still stopped eating. I don’t recommend this product. I got a new UV bulb and barely extract instead.

Rated 1 out of 5 stars
By Rachel on Jun 20, 2022

Doesn't seem to be working

I have used it every three days since getting it and it hasn't made any difference. I can only add one mL at a time per the instructions and I don't want to harm my fish by adding more. I am also using a UV device designed to clear the water but it's not working either. My next step is to drain the tank and add all new, clear water then treat it and pray the green doesn't come back.

Rated 1 out of 5 stars
By Delaney on Jul 31, 2022


I added not 1/4 is the amount your supposed to add to my aquarium and it killed every single one of fish. I am so upset.

Rated 4 out of 5 stars
By klew on Mar 26, 2022

User error

The first 2x I used this, I followed the directions exactly. I didn't really see much of an improvement. Maybe a little but nothing major. During a water change...my husband accidentally tripled the dose! Let's just say I have one very clear fish tank but nothing to look at. It was our fault and not the product but just a warning if anyone gets risky with the dose and thinking they should use more. It most definitely will kill the fish if you aren't careful!