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

When it comes to the ongoing maintenance of an aquarium, there are many challenges that every dedicated fishkeeper must face in order to keep their tank as clean and healthy as possible. It’s only with continuous care that a tank can thrive, and one such issue that you’re likely to face is the management of algae. Fast growing, stubborn and hard to remove, keeping algae under control is a common trial for beginners and experienced fishkeepers alike, but it doesn’t need to be a difficult one. 

In this blog, our experts will detail all you need to know about managing algae, including what aquarium algae is, why too much of it can be dangerous, and the best ways to keep it from overwhelming your underwater ecosystem. Here to help you keep your aquarium clean and clear, we’ll also provide you with a list of the best algae-eating fish to add to your tropical aquarium so that you and your tank inhabitants can work together to keep your water algae-free.

Why is my fish tank growing algae?

Before we get into the best ways of removing algae from a fish tank, and the most effective types of algae-eating fish, we should first cover what this plant-like pest is and why it’s growing in your aquarium.

First and foremost, the growth of algae in fish tanks is caused by environmental imbalances. Namely, high levels of phosphorus, organics and nitrates are the key elements to keep an eye on, especially when combined with an excess amount of light, as these are the conditions that algae needs to thrive. 

Algae is also a ‘protist’, a type of living organism that reproduces asexually, so its growth can spiral out of control incredibly quickly. Fortunately, there are plenty of techniques for keeping algae growth to a minimum, and it’s certainly not all bad news - in fact, there are a few benefits to having a well-managed amount of algae in your aquarium.

Is algae good for a fish tank?

When kept to a minimum, yes - having some algae can be good for a fish tank. It’s only the overgrowth of algae that threatens the happy balance of a tank. Some benefits of algae include:


While not a look that every fishkeeper will go for, having a little algae growth can bring a natural, almost peaceful appearance to your tank. After all, algae is completely natural and is found in seas, lakes and ponds around the world, so having some algae climbing across rocks and decorations can create a striking appearance.

Source of Vitamin A

A tasty snack for some types of fish and invertebrates, if you have algae in your tank it's likely that its inhabitants will happily graze on the surface. This is particularly good as algae is a natural source of carotene, an important vitamin which helps with the production of vitamin A. Vitamin A, in turn, helps to keep fish looking bright, shiny and vibrant.

Natural Filtration

Some types of fish tank algae, such as brown algae and green hair algae, offer a unique benefit to fish tanks - namely they can assist with the natural filtration process. Helping to reduce the level of nitrates and other harmful toxins often found in fish tanks, these algae types can actually work to create a safer environment for your fish.

Is algae bad for a fish?

Though not as evil as some fishkeepers may fear, algae can pose a threat to your fish and plant life when left to grow out of control. The main damage that an algae overgrowth can inflict on your tank environment is a lack of oxygen. A key requirement of continued growth, algae will absorb as much oxygen as it can from its environment, starving your fish of it and risking their health. This isn’t a problem when there’s only a small amount of algae, as there’s a limit to how much oxygen it can absorb, but when left to grow to excessive levels this threat starts to appear.

How to get rid of algae in a fish tank?

Not a one-time fix by any means, getting rid of aquarium algae is more a case of repeated effort and treatments to keep levels at a minimum than saying goodbye to it forever. Fortunately, there are some easy methods you can try, many of which can be integrated with your usual cleaning schedule for an easy, stress-free routine you can stick to. 

To help you find the best method for you, we’ve detailed our favourite approaches to managing algae below, including water treatments, cleaning suggestions (with recommendations of the best tools for the job), preventative steps to slow growth, and the best algae-eating fish for tropical aquariums.

Method 1: Slow algae growth

As algae overgrowth is caused by an imbalance in a tank’s delicate ecosystem, one of the best steps you can take to reduce its growth in the long run is to make efforts to re-balance the elements they need to grow. This isn’t a perfect science, and even the most experienced enthusiasts will struggle to get the balance between light, oxygen, phosphates, nitrates and organics exactly right, but there are still some easy changes that will help to reduce algae growth.

    • Reduce your tank’s exposure to light. Excess light is a key component to algae overgrowth, so the first thing you should do to limit growth is to first reduce the amount of light your tank receives. On average, your tank should receive between 8 - 12 hours of light per day, with freshwater fish-only tanks coming on the lower end of the scale, and reef tanks on the higher. This can be cut down further to slow the spread of algae, but we recommend keeping a close eye on your fish, plants and corals to make sure they aren’t deprived of too much light.
    • Avoid overfeeding. Another component which can lead to the overgrowth of algae is the imbalance of nitrates in the water. High nitrate levels can be caused by a range of factors, but more often than not it is the result of overfeeding. To avoid the overproduction of waste from overfed fish, and the rotting of uneaten food, we recommend limiting the amount of food you add to your tank to only what your fish eat within 5 minutes. For more advice on how to avoid overfeeding, read through our guide on how to buy the right fish food.
    • Maintain your water quality. It's important when tackling algae to ensure that your water quality is kept at a good level, and that pollutants and other contaminants are removed. This means performing regular partial water changes, and making sure to replace lost water with purified tap water. This is particularly important as regular tap water contains fertilisers that are bad for your fish, while helping your algae to grow.
    • Add plants to your aquarium. A favourite method of combating algae growth, planted aquariums act as natural competition for light, space and nutrients: all things algae needs to thrive. Beyond helping to starve algae of its favourite conditions, plants in fish tanks also offer a range of benefits for fishkeepers including creating a beautiful environment, absorbing CO2 and unwanted nutrients, and boosting oxygen production. If you’re considering using plants to reduce algae, read through our Guide to Aquarium Plants to learn more about how to plant and care for them.

Method 2: Manually remove unwanted algae

If you’ve adopted the various steps of method one into your regular aquarium care routine, you’ll hopefully have seen a reduction in the growth speed of algae. Another way to take this further is to manually remove unwanted algae. This allows you to see instant results and gives you a clean start to try and keep on top of.

If you’re removing algae from your fish tank using this manual method, there are a few things you’ll want to add to your cleaning arsenal. In particular, we recommend investing in an algae scrubber or scraper for glass and acrylic aquariums, such as the Seachem Algae Scraper, as well as an aquarium syphon cleaner such as the Fluval Gravel Vac to help clear algae from substrate.

Seachem Algae Scraper, from £22.95


Fluval Gravel Vac - Small/Medium, £15.45

Method 3: Use fish and plant-friendly algae treatments

Once your fish tank is in better shape and algae isn’t climbing over every available surface, another effective method to try is the addition of aquarium algae treatments. Unfortunately, many algae treatments on the market can be damaging to your fish and plant life, and some are only suitable for certain types of tanks, so it's important to be very careful when selecting the right solution for you. 

To help you protect your tank inhabitants, we’ve listed three of the best algae treatments for fish tanks below, along with advice on when they're suitable to be used.

  1. Tetra Algumin Algae Treatment, from £7.29

Suitable for use in freshwater aquariums, Tetra’s Algumin Algae Treatment is a biological which is designed to effectively combat all types of commonly-occurring algae. When dose recommendations are closely followed, this treatment is harmless to all freshwater tank inhabitants, including fish, plants and microorganisms.

  1. NT Labs Algae Gone, £11.99

Perfect for fishkeepers looking for a fast, easy solution, NT Labs’ Algae Gone is designed to combat algae, green and cloudy water in a single dose. It does this by clumping particles together, which can then be handled by your tank’s filtration system. This option can be used in both tropical and coldwater aquariums, and is plant and shrimp safe. 

  1. API Prevent Algae, from £9.79

Lastly, API’s Prevent Algae solution is designed to target the food supply that algae needs to thrive, namely phosphates. With this essential nutrient removed, algae is starved of what it needs to grow. An ongoing treatment which should be added in doses on a weekly basis, Prevent Algae is suitable for freshwater and saltwater aquariums and is safe for use in tanks with fish, plants, corals and invertebrates.

Method 4: Add algae eating fish to your tank

Last but not least, our final suggested method on controlling algae is to introduce some algae-eating species into your tank. As with the algae treatments, the type of species you can add to your tank will depend on the type that you have, so we’ve put together a list below to help you decide which algae-eating fish, snails and shrimp can live in your tropical aquarium.

One thing to keep in mind when introducing any algae eating fish to your aquarium, whether you’re choosing from our list or going off a recommendation from a fellow fishkeeper, is that your new tank inhabitants will need a suitable source of aquarium food. Contrary to popular belief, algae eating fish should not just be left to survive on algae, and will need a varied diet just as much as any other fish.

Best algae-eating fish for a tropical tank

Siamese Algae Eater

  • Size: 6 inches
  • Ideal pH: 6.5 - 8.0
  • Ideal water temperature: 24 - 26 °C
  • Ideal tank size: Medium - Large (minimum of 30 gallons)

Easy to care for and endlessly helpful, the clue is in the name when it comes to the Siamese Algae Eater. A hungry little fish which is affectionately likened to a rubbish bin by many fishkeepers, the Siamese Algae Eater will happily nibble away at algae growing on the surface of your tank, and will help itself to other snacks available to it, including leftover foods that have sunken to the bottom of the tank.

Additional traits that make this tropical algae-eater a favourite among beginners and enthusiasts alike is its easy going nature. A peaceful neighbour to most other species, the only thing you need to watch out for with the Siamese Algae Eater is their tendency to jump - so if you add a few of these to your tank be sure to keep the lid tightly closed.

Bristlenose Plecostomus (Bristlenose plecos)

  • Size: 5 inches
  • Ideal pH: 5.8 - 7.8
  • Ideal water temperature: 23-27°C
  • Ideal tank size: Medium (minimum of 20 gallons)

A small breed of catfish that are particularly striking in appearance, the Bristlenose Plecostomus are another efficient type of algae-eater for a tropical aquarium. Not unlike the Siamese Algae Eater, the Bristlenose Plecos is known for its ability to chomp its way through algae while peacefully living alongside a range of other species. 

In terms of ideal living conditions, this particular type of fish prefers to stay at the bottom of its tank, keeping close to hiding spaces such as small cave-like ornaments and pieces of driftwood. One thing to note is that they eat quite a lot, so if your algae growth is minimal, consider dropping some sinking pellets into the tank to keep them well fed.

Otocinclus Catfish (Otos)

  • Size: 1 - 2 inches
  • Ideal pH: 6.8 - 7.5
  • Ideal water temperature: 22 - 26°C
  • Ideal tank size: Small - Large (minimum of 10 gallons)

While popular breeds of tropical algae-eaters such as the Siamese and Bristlenose are ideal for managing algae in a medium to large tank, those with smaller aquariums can rely on the Otocinclus Catfish. Sometimes called a Dwarf Sucker, these little fish measure between 1 - 2 inches in length, and are known for picking away algae from very small nooks and crannies, such as tank corners and the tiny dips of an intricate decoration. 

Even as small as they are, Otos have a sizable appetite, so if naturally-occurring 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 (minimum of 30 gallons) 

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. Growing up to 10 inches long, and semi-aggressive to some fish (particularly those who are close in size and colouring), it's recommended that these fish don’t be kept in pairs. In order to keep aggressive behaviour to a minimum and maintain the harmony in your tank, Chinese Algae Eaters should be given plenty of space to swim, meaning medium to large tanks that aren’t overcrowded are most suitable.

Another important thing to keep in mind with this species of algae eater is that they have particularly large appetites, especially as adults. If they don’t have access to a suitable diet, they have been known to latch onto larger fish to eat their slime coat. This can pose a significant threat to the larger fish as they can become injured and leave them open to infection.

Nerite Snail

  • Size: 3 cm
  • Ideal pH: 7.0 - 8.0
  • Ideal water temperature: 23 - 28°C
  • Ideal tank size: Small - Large 

The most popular of all algae-eating snails, Nerite Snails are a favourite of many freshwater fishkeepers thanks to the impressive patterns on their shells. The Tiger Nerite Snail (pictured above) for example, has a tiger-like stripe pattern which makes it a striking addition to any tank. These little creatures are as functional as they are enjoyable to look at, and are happy to eat all types of algae and so do a great job of keeping your tank clean.

As with a lot of snails, shrimp and other invertebrates, including the others included in this list, they are likely to be targeted by large fish like Cichlids and Loaches. Because of this, if you have large fish in your tank, then we don’t recommend introducing these more vulnerable species into the mix.

Apple Snail / Golden Mystery Snail

  • Size: 10 cm
  • Ideal pH: 7.2 - 7.5
  • Ideal water temperature: 20 - 28°C
  • Ideal tank size: Small - Large

A snail of many names, the Apple Snail (also known as the Golden Mystery Snail, Golden Inca Snail and Yellow Snail) are effective algae eaters and eye-catching tank inhabitants. Golden yellow in colour, these beautiful snails are easy to take care of and prefer sharing their space with other non-aggressive tank mates. Another thing to keep in mind when caring for a scavenger like the Apple Snail is that they have a good appetite, which should be supplemented with algae wafers to ensure they have enough to eat.

Red Cherry Shrimp

  • Size: 1 - 2 inches
  • Ideal pH: 7.0 - 7.8
  • Ideal water temperature: 22 - 26°C
  • Ideal tank size: Small - Large

Another stunning addition to any freshwater tank, the Red Cherry Shrimp will gladly assist you with your algae issue. This little critter will chomp away at any green or brown growing across ornaments and tank glass, and will also happily enjoy other traditional fish food options including shrimp pellets, sinking pellets and algae wafers. Natural explorers, it's also a good idea to introduce some additional elements into your aquarium along with the Red Cherry Shrimp to keep them entertained and happy, such as a sponge filter (which they’ll enjoy picking trapped food from) and some air stones (which will improve water circulation).

Amano Shrimp

  • Size: 2 inches
  • Ideal pH: 6.0 - 7.0
  • Ideal water temperature: 22 - 26°C
  • Ideal tank size: Small - Large (minimum of 10 gallons)

A species which thrives in a planted environment, Amano Shrimp are friendly little creatures who prefer to live in groups of six or more. Though peaceful and dutiful algae eaters, they have some interesting behaviours that make them particularly entertaining tank inhabitants to have. In particular, when they shed their shells (which happens roughly once per month) they tend to go into hiding. In contrast, when feeding time comes around they tend to become more frantic and excitable.

Whiptail Catfish

  • Size: 6 - 8 inches
  • Ideal pH: 6.5 - 7.0
  • Ideal water temperature: 22 - 26°C
  • Ideal tank size: Large

For fishkeepers struggling to manage algae levels in a larger tank, Whiptail Catfish are an ideal choice. Almost reptilic in appearance, and particularly happy in peaceful tanks with other non-aggressive species, these fish are bottom dwellers and like to spend most of their time resting on sandy substrates. In terms of diet, they like to eat algae, but also require some additional food such as sinking pellets, blanched vegetables and bogwood.

Twig Catfish

  • Size: 4 - 6 inches
  • Ideal pH: 6.5 - 7.5
  • Ideal water temperature: 22 - 26°C
  • Ideal tank size: Medium - Large

Not the easiest algae-eating fish to look after (hence their low placement on our list) Twig Catfish require more specialised care than some of the other species on this list, and shouldn’t be taken on by beginners. Happiest when kept in pairs, this freshwater algae-eater is shy and peaceful in nature, and prefers not to be kept with larger fish as they tend to be easily stressed when confronted.

Tackle algae in your fish tank with Aquacadabra

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. If you’re looking for more help, simply get in touch with us by filling out our contact form.