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What are the best algae-eating fish for my tropical fish tank?

Maintaining your tank properly is key in order to keep your fish happy and healthy, and also to keep your tank looking lovely and clean. 

As all tank owners will know, algae comes with the territory. It is completely natural to see algae growth within your tank and doesn’t mean you have done anything wrong. In fact, depending on the look you are going for, a little algae can look good and add to the aesthetic of your tank. However, too much algae can cause you problems, and it grows rapidly too, so properly managing algae growth in your tank is important. 

In this guide, we explain more about why too much algae growth is bad, what you can do as a fish tank owner to control algae growth and which fish you can add to your tank that will eat the algae. 

What is algae and is it bad for my fish tank?

Algae is a ‘protist’ - which is a group of living organisms that reproduces asexually. This is why its growth can spiral if it’s not effectively controlled. 

It’s important to point out that having algae in your tank is not all bad news. Some good things about algae include: 


As we mentioned above, a little algae growth in your tank can look nice. After all, algae is completely natural and is found in seas, lakes and ponds around the world, so having some algae on rocks or decorations in your tank can look pretty cool and give your tank a natural look. 


Certain types of algae can also be particularly good for your fish tank - namely brown algae and green hair algae, as these types can assist with the filtration of nitrates and harmful toxins. 

Vitamin A

Another good thing about having a bit of algae in your tank is that it produces carotene, an important vitamin that helps with the production of vitamin A. Vitamin A helps keep the colour of your fish looking bright, shiny and vibrant. Unfortunately, fish cannot produce carotene by themselves, which makes algae a valuable source of vitamin A and keeps your fish looking and feeling healthy.

However be warned, in order for algae to survive and grow it uses the dissolved oxygen in the water. This means that the more algae you have in your tank, the more oxygen it’s using up and so there is less oxygen available for your fish. 

Ultimately, if there is not enough oxygen in your water because you have far too much algae, which is common due to its rapid growth rate, then your fish may be starved of oxygen. That’s why managing its growth is so important.

Steps you can take to control the growth of algae in your fish tank

Different types of algae call for different types of treatment. Below, we have listed some of the best initial steps that you can take to control the growth of algae in your tank and suggest what fish you should introduce to eat algae.

Step 1: Manually clean existing unwanted algae from your tank

There are many ways you can clear unwanted algae from your tank by intervening yourself. This is commonly done using an algae scraper. If you invest in a good one, then removing the algae won’t be hard work. We recommend using a Seachem algae scraper which features three retractable blades and is suitable for both glass and acrylic aquariums.

If you like the look of algae on the back of your tank but not on the glass, then consider using a magnetic glass cleaner. These magnetic tank cleaners will clean stubborn algae and dirt from the inside of your glass tank without leaving any scratches.

Alternatively, you can invest in a new fish tank or self-cleaning fish tank, which will take care of the hard work for you! 

Step 2: Invest in a fish and plant-friendly algae treatment

Not all algae treatment solutions out there are fish-friendly, so make sure when looking for a liquid treatment for your algae that you do your research. If you have an indoor freshwater tank, then we highly recommend Tetra Algumin, an algae treatment that when used correctly will combat all commonly-occuring algae without harming any fish or plants that call your tank home. 

Step 3: Check for human error 

Aquarium ecosystems are complex things. Successfully keeping one thriving requires the perfect balance of a lot of things - water temperature, mineral density, filtration, oxygen levels, pH, lighting, planting, fish compatibility and the list really does go on. 

Because the balance is so delicate a lot can go wrong - even for the most experienced enthusiast. Some things to look for that could help you to solve your algae problem include:

  • Too much light
  • Algae needs light to survive, so perhaps your tank is getting too much? If you think this might be the reason then try and cut down the brightness and duration of your lighting. To take this solution to its most extreme, you can even blackout your tank completely for the majority of the day. If you have plants and corals, you’ll still need six hours of strong light per day. If your tank is a fish-only tank, then your fish could be happy with as little as four hours of light. 

  • Using unpurified mains / tap water
  • Now, if you are new to keeping fish then you may just be using tap water to fill your tank. Tap water contains all sorts of fertilisers and if your algae situation is already escalating quickly then using tap water is like adding fuel to a fire. 

    Try purifying your tap water through an RO unit. RO stands for reverse osmosis and these units remove the pollutants and fertilisers in the water. It will also dechlorinate it too, leaving you with purified water that is safe for your fish and isn’t creating a perfect storm for algae growth. 

  • Not changing your water frequently enough
  • Changing water in your tank can be a pain, but it is necessary. Regular water changes are important in fresh and saltwater tanks in your fight against algae, so if you know you have been guilty of not changing your water frequently, then try to make this more habitual. 

    Step 4: Introduce algae eating species

    Last but not least, you can introduce some algae-eating species into your tank. Now, our suggestions for this will depend on whether you have a freshwater or tropical tank. So, to make sure we give you the best advice, we have made two lists. The first, algae eating fish, plants and more that will feed on algae in a freshwater tank and the second, a similar list for tropical tanks. 

    Best algae-eating species for tropical tanks

  • Siamese Algae Eater

  • Size: 2 inches

    Ideal PH: 6.5-8.0

    Ideal water temperature: 24–26 °C

    Ideal tank size: Small - Large

    Although only two inches in size, we would recommend the Siamese Algae Eater for medium to large tanks. With this algae-eating fish, the clue is in the name. It’s a brilliant algae eater and we consider it to be an all-round ‘rubbish bin’ - as this little guy will clean up leftover pellets and flake foods, live foods and veg. 

    It’s also a good choice for fresh tank owners as in general it gets on well with most other fish and is easy to care for. To keep your Siamese Algae Eaters happy, make sure they have plenty of oxygen and they enjoy a tank temperature of about 25 degrees. 

    If you have a huge algae problem that needs resolving and are relying on these guys to handle a large amount, then don’t be tempted to add a dozen of them into your tank. They are territorial cleaning machines, so any more than three or four per 100 litres would result in some conflict. Oh - and they jump too - so keep the lid firmly on your tank to avoid an overboard situation. 

  • Bristlenose Plecostomus (Bristlenose plecos)

  • Size: 4-5 inches

    Ideal PH: 5.5-7.6

    Ideal water temperature: 23-27°C

    Ideal tank size: Medium

    If you’re looking for something that can do the job well but is also pretty to look at, then we recommend checking out the Bristlenose Plecostomus. They are peaceful fish growing to about 4 inches and are available in three colours - gold, albino and black and white spotted. Perfect for a medium-sized tank, these guys like to hide for most of the day, so giving them some driftwood and hiding places will help them out - particularly if you have more aggressive fish that they need to cohabit with. One thing to note is that they eat quite a lot, so if you run out of algae or are running low, consider dropping some algae pellets into the tank to keep them well fed.


  • Otocinclus Catfish (Otos)

  • Size: 2 inches

    Ideal PH: 6.8-7.5

    Ideal water temperature: 22-27°C

    Ideal tank size: Small - Large

    We’re trying to cover all bases with this list - so that we recommend an algae-eating fish suitable for all sizes of tank. The Otocinclus Catfish, also known as a dwarf sucker fish, is the ideal little algae-eating fish for a small-sized  tank. If you have a small tank or algae in very small nooks and crannies in your tank (perhaps in the corners of an intricate decoration), then the Otos will be able to get there. 

    For little guys the Otos have a huge appetite. If naturally-occuring algae is lacking, then supplement the diet with fish-friendly vegetation like a little bit of courgette. 


  • Chinese Algae Eater

  • Size: 10 inches

    Ideal PH: 5.8-8.0

    Ideal water temperature: 24-27°C

    Ideal tank size: Medium-Large

    If you’re looking for a more substantial algae eater that can keep up with more aggressive fish, then the Chinese Algae Eater might be your best bet. They grow up to 10 inches long so they will need a medium-large tank ideally. 

    Be warned though, they are far more efficient in their youth and move on to a more protein-based diet when they are older. They also need a lot of feeding when fully grown and if they can’t find enough algae in the tank then they may start latching onto the other fish in your tank to eat their slime coat. Essentially, these fish are more useful when they are younger and so over time you may want to introduce some new and more youthful Chinese Algae Eaters into your tank (and ensure the older ones remain well fed). 


  • Nerite Snail

  • Size: 3cm

    Ideal PH: 7.0-8.0

    Ideal water temperature: 23-28°C

    Ideal tank size: Small-Large 

    Nerites are the most popular of all algae-eating snails. They have tiger-like stripes on their shells so they are enjoyable to look at. They also eat all types of algae and so do a great job of keeping your tank clean. As with a lot of snails and shrimp (certainly the ones in this list), they will be targeted by large fish like Cichlids and Loaches so if you have these in your tank then we don’t recommend introducing the more vulnerable fish, snails and shrimp found in this list. 


  • Apple Snail / Golden Mystery Snail

  • Size: 10 inches

    Ideal PH: 7.6-8.4

    Ideal water temperature: 20-29°C

    Ideal tank size: Small-Large

    As well as being an effective algae eater, it has a cool name and it’s massive (upto 10 inches when fully grown). If you buy one of these for your tank chances are it will be tiny at the time of purchase so be mindful that it will grow to a substantial size. Because of its growth rate and size, it eats a lot. The Mystery Apple Snail will eat most kinds of algae as well as leftover food but make sure it’s well fed as it does eat plants. 

  • Red Cherry Shrimp

  • Size: 1-2 inches

    Ideal PH: 7.0-7.8

    Ideal water temperature: 22-26°C

    Ideal tank size: Small-Large

    The red cherry shrimp is a stunning little critter that will gladly assist you with your algae issue. They are a popular choice because they look striking and so they bring more to the tank than just their algae-eating ability. They are delicate little things and can be bullied and considered food by larger fish so it’s always best to keep them with other small fish. 


  • Amano Shrimp

  • Size: 2 inches

    Ideal PH: 6.0-7.0

    Ideal water temperature: 22-26°C

    Ideal tank size: Small - Large

    Amano shrimp tend to hold up a little better than cherry shrimp, which makes them more popular for enthusiasts with a community tank. They also have the edge when it comes to efficiently taking care of your algae, and will take care of decaying plant matter and left over fish food too, so they are a popular choice. They do better in groups of six or more, so try not to buy just one or two. 

  • Whiptail Catfish

  • Size: 6 inches

    Ideal PH: 6.5-7.0

    Ideal water temperature: 22-26°C

    Ideal tank size: Large

    If you have a large enough tank, then the Whiptail Catfish is a nice-looking fish that can help you with your algae issue. They are peaceful and should not be kept with aggressive fish. As well as algae, the Whiptail Catfish will eat leftover fish food, blanched vegetables and bogwood. It’s important to note that the Whiptail can’t live off algae alone, so be sure to supplement their diet. 


  • Twig Catfish

  • Size: 4 inches

    Ideal PH: 6.0-8.0

    Ideal water temperature: 20-24°C

    Ideal tank size: Medium - Large

    We have placed the Twig Catfish fairly low down on our list, as it requires more specialised care than some of the other species on this list. This might not make it a great choice for beginners. The Twig Catfish will do best in pairs and eat most algae types that you might find in your tank. 

    We hope this guide was useful for you and helps you to find a solution to your algae issue. Of course, every tank is different, so it’s best to think about your tank size, temperature, PH, tank cleaning regime and how effective your aquarium components are to come up with a bespoke solution that works for you. If you’re still not sure, then we welcome customers to get in touch with us to receive bespoke advice, particularly when it comes to tank upgrades and components that could provide you with a long-term solution and keep your aquarium algae under control.