Noone likes a green, algae-filled tank, except for these algae eaters that is! Here’s the Swell Guide to the best algae eaters for your aquarium.

Bristlenose pleco, Ancistrus spp.

Bristlenose catfish from the genus Ancistrus are brilliant all-round algae eaters. They don’t get too big like Common and Sailfin plecs do and the tank bred ones are hardy with regard to pH and temperature. Bristlenose plecos even breed in the average community tank. Perfect for all tropical aquariums over 75cm in length and one of the best algae eating fish. Recommended.

Sucker catfish, Otocinclus catfish, Otocinclus spp.

Otocinclus catfish as they are also known are the smallest members of the Pleco family, making them perfect for nano tanks and planted tanks. At just a few cm in length, you can employ a small army of six or more to rasp away at wood, rocks and plant leaves.

Native to South America, they prefer a low pH balance and can be delicate when first imported but once settled they’ll do a great job of algae-eating and you’ll hardly know they’re there. They stay under 2 inches when fully grown.

Black mollies, Poecilia sphenops

Black mollies aren’t on the radar of many algae battlers but those upturned lips are great at rasping all types of algae from all surfaces including wood, rock and plant leaves. They do prefer hard tap water and even salty, brackish water, but Platies and even Guppies do a similarly good job. You’ll be surprised! They average 2 inches long when adult, but Black sailfin mollies can exceed 3 inches.

Siamese algae eater, Crossocheilus siamensis

Siamese algae eaters are wonderful for eating green hair algae and are also often prescribed for eating nuisance Black beard algae. The downside is their eventual size of six inches and the fact that they should really be kept in groups in long, stream-styled aquariums. They can jump too. But definitely an “A” list algae eater. 

Siamese algae eaters are sometimes called Siamese Flying Fox. Not to be confused with the true Flying Fox, Epalzeorhynchos kaloptetus, which although it also grazes algae it doesn't eat BBA and can become territorial like its "shark" cousins. Flying Fox can obtain a length of 5 inches in large aquaria.

World’s best algae eater, Crossocheilus reticulatus

It’s a big title to live up to but about 20 years ago a plain-looking species called Crossocheilus reticulatus was marketed as World’s Best Algae Eater by its suppliers.

A relative of the Siamese algae eater, it is indeed very good, but like the Siamese, it also prefers to be in shoals in big tanks. If you have a big tank and you see some for sale - definitely worth a try. 

Sucking loach, Chinese algae eaters, Gyrinocheilus aymonieri

Also known as the Chinese algae eater, Gyrinocheilus aymonieri are very hardy and can also be kept in unheated aquariums. As small fish, they are busy, very effective algae eaters and more suitable than Hillstream Loach.

The problem is the Chinese Algae Eater grow larger and more territorial when they exceed 6 inches, so although a good short term fix, they may be problematic in the long term and only suitable then to be mixed with tough fish in large tanks. A golden variant is also available.  

Garra, Garra spp.

Garra species also come under the “sucking loach” catch-all and come from rivers in streams in South East Asia. Most are plain but some are colourful and some even develop horns on their heads as they mature.

All are very good algae eaters although they suit fast-flowing, cool, stream-style aquariums and can be territorial as they grow and mature. Most average 4 inches as adults in the aquariums.

Algae eating shrimp, Caridina spp.

The Algae eating shrimp is Caridina multidentata, also known as the Amano shrimp after Takashi Amano, the man who introduced its use and algae-eating benefits to the wider fishkeeping world.

Amano shrimp are the perfect algae eater for nano tanks and planted tanks which don’t contain large fish, working tirelessly, 24 hours per day. Its also often combined with Otocinclus or even Siamese algae eaters in larger planted tanks and many people who keep them for the time instantly fall in love with them.

There are dozens of other tiny freshwater algae eating shrimp too including Cherry shrimp, Crystal reds and all their variations, and all make wonderful but tiny algae eaters.

Being invertebrates, they bring another dimension to the planted aquarium. Armoured shrimp and Bamboo shrimp don't eat algae however, being filter feeders, and ghost shrimp use their tiny claws to grab food, not eating algae.

Don't mix shrimp with predatory fish. They'll eat them!

What is the best algae eater?

It depends on tank size and the type of algae, but Bristlenose catfish are very good in medium tanks. For nano tanks, planted tanks or tiny unheated tanks, Cherry shrimp are good too, and bright red. Algae eaters are an integral part of every healthy aquarium.

Do algae eaters keep tank clean?

If the aquarium algae is green and nutritious the above fish and invertebrates will eat it and "clean'" the tank of it. But they won't clean in a regimented way, they won't eat the poo of other fish or substitute essential filter cleans, water changes and tank maintenance. Its the same with catfish and loach species labelled as bottom feeders.

All algae eating fish and shrimp will actually add to the amount of waste produced because they go to the toilet too, and what goes in must come out.

What do algae eaters eat?

In the wild our algae eating fish may eat lots of different things including dead plants, aquatic invertebrates, wood, fruit, seeds and leaves. Even dead animals! Often it's what inside the algae, like tiny invertebrates, that offer them the extra nutrients they need.

Algae is often nutrient-poor and that's why it's not the only thing they should be expected to live on in your tank. Plecos that are forced to get by on uneaten fish food often suffer from bloat. Feed something solid that they can rasp on and meets their nutritional needs instead.

In the aquarium, algae-eating fish and shrimp should be offered sinking food pellets, granules and tablets, algae wafers, plant based foods, wood, leaves, and even green vegetables like cucumber and courgette. Some will even eat live food like Tubifex worms and Bloodworm.

What eats algae in freshwater?

We've listed eight of our favourites above but there are literally hundreds of species that will eat algae, and hopefully something to suit every size and temperature of tank.

The important thing to remember is the eventual adult size that any fish species can attain, what it can coincide peacefully with and that ALL algae eaters must also be fed supplemental foods to give them all the key nutrients and vitamins that they need to survive and thrive.

It's not just about having enough algae. It's about providing other foods as well.

Are there any algae eating snails?

Freshwater snails are often bought to eat algae, but depending on the species, they aren't the most effective algae eaters.

The Rabbit snail eats plants, whereas the Apple snail prefers to dine on decaying plant matter, crawl out and lay bright pink eggs everywhere. Tadpole snails and Malaysian trumpet snails prefer leftover fish food and can reach plague proportions in tanks that are overfed.

The Ramshorn snail will eat soft algae but the Nerite snail is the best algae eating snail in tanks that contain smooth rocks for them to cling to, and nerite snails are the only snail species to tackle hard diatom algae and green spot algae. They could be combined with the popular freshwater fish recommended above.

What algae don't they eat?

Algae eating fish and shrimp will only eat lush, bright green algae growth, and won't graze Brown algae or Slime algae, which is a bacteria. They will also eat some left over fish food, although flake food is unsuitable for them long term.