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Algae Eaters for the Freshwater Aquarium
An illustrated guide to the most popular options

 Age of Aquariums > Aquarium Articles


The most important part of fighting excessive algae growth in aquariums is by nutrient control, as already covered in the articles Algae Control! and Freshwater Algae Types: An Illustrated Guide in this section, but a lot of help can be given by adding algae-eating fish and invertebrates as part of your aquarium population.

Algae eaters are a great addition to any aquarium really, but it is important to regard them with the same status you give to all your other watery pets, making sure that you choose compatible species for your aquarium, and that you're providing them with what they need to live well in the long term. An exception is the case where you have several tanks and then you can move algae eaters temporarily into one tank to help with algae combat, and them bring them back to their home tank when you're satisfied with the results. Always keep in mind though, that they are helpers - algae combat is a daily concern that will always be your responsibility. Avoid making the very common mistake of thinking that just by adding an algae eater to your tank you can now forget about the issue!

The most effective way of using algae eaters to help you keep algae low in your tank is to add different types of algae eaters, because not all eat the same algae, nor from the same type of surface. A combination of snails, shrimps and algae-eating fish is a good way to go. But again, always check for compatibility and fish/invertebrate requirements, please. It is much better to keep them in planted aquariums, since the food sources are wider. NOTE: in general algae-eaters will eat less algae if overfed with commercial food, so try to find just the right amount of feeding so they will be healthy while still scavenging for algae and leftover food.

Now that you know the basics, let's see some of the more popular options you have, more or less listed as a "Top 10 Ranking" in terms of the best or most efficient animals:

Siamese Algae Eater

1. Siamese Algae Eater
also known as SAE (Crossocheilus siamensis), this fish is a useful algae eater, eating thread algae and the brush algae ignored by other fish. They also eat planarians (flatworms) which can become a nuisance in the aquarium. SAE can be slightly territorial with their own species so they are probably best kept either single or as a group of 5 or more in large tanks. Unlike the Chinese Algae Eaters, the Siamese Algae Eaters will eat lots of algae. The more common Chinese Algae Eater stops eating algae as it grows larger, becomes aggressive, and tends to annoy other fish. Minimum tank size for a pair of adult Siamese Algae Eaters is 100 liters. The aquarium should be long and have lots of living plants. As they are not aggressive, they can be kept in any big enough community tank. Their active behavior might stress some sensitive species like dwarf cichlids and prevent them from spawning. They are related to Red-tailed Sharks and similar species and should not be kept with them unless the aquarium is large and well planted, because these species are often aggressive towards all their relatives.

A very hardy fish, it is easy to keep and feed, eating both algae and just about anything else put into the tank, such as flake food, pellets, live foods, parboiled vegetables, etc. It does a diligent job of removing algae from plants without harming them, as well as from decorations and aquarium glass. Considered by many aquarists as a necessity in any well-planted aquarium. Cover the tank carefully however, as these fish are strong jumpers. SAE grow up to 14 cm, need a well filtered, oxygenated water with a pH around 7 and temperature 25C. If keeping SAE, make sure to have a lot of living plants. More info can be found in the Siamese Algae Eater page in the Gallery section.

Amano Shrimp 2. Amano Shrimp
also known as Yamato Numa Ebi (Caridina japonica), is one of the best algae eater shrimps available these days. Besides eating algae, it also consumes dead plant detritus and cleans up leftover food. They are very busy eaters. Their size doesn't go over 5 cm (males are a bit smaller at 3.5 cm) which makes them very suitable for smaller aquariums. They are known to eat all algae except the Green Spot algae and Blue-Green Algae. Appetite for algae will decrease if commercial food is given on a regular basis. It is good to keep this shrimp in groups of 3 and up. Note: they should be given something to cling onto inside the bag during the transport. In planted tanks, one should be careful with dosing fertilisers. Low light tanks do not need as much as the high light tanks. All fertilisers contain a small amount of copper that is very dangerous for shrimps. To ensure that this element doesn't accumulate over time, it is essential to do weekly water change 30-50%. Aquarium water should be treated with dechlorinators, because chlorine and chloramine are dangerous for shrimps. Bigger fish and most Cichlid species will eat these shrimp, so it is advised to house them only with smaller, placid fish species. More info about Amano Shrimp can be found in the Gallery section.

Oto Catfish 3. Oto Catfish
Part of a large family of Loricariidae found in rapidly moving rivers throughout most of South America, the Otocinclus spp. are among the smallest species. Oto catfish grow up to 5 cm, which makes them suitable for smaller aquariums. They are usually tan with a black peppered body. Otos should be kept in planted tanks only! They do much better if kept as a small group. Otos are the best plant leaf cleaners and will remove almost all algae from it without damaging the leaf. They will ignore the grown algae, but will eat young algal growth and by doing that will keep the algae very low. Like all catfish, these one enjoy the presence of bogwood, so adding a piece to the aquarium would be a good idea. If there isn't enough algae in the aquarium, Otos should be fed with blanched zucchini once a week, boiled for 2 minutes and cooled down before feeding. Place the zucchini on the bottom or, even better, on the piece of bog-wood where the Oto will come readily and notice the vegetable. Do not leave the zucchini for longer than two days inside the tank and not shorter than a day. It's been known that Otos will ignore sinking catfish tablets and algae wafers, and will ignore most of other vegetables like lettuce, spinach, cucumber, etc. Zucchini is the best proven feeding choice. Some aquarists farm algae and than introduce them as Oto food. It's been known that Otos relish brown algae (diatoms). One of the best ways to ensure that Otos will have sufficient algae is to keep one Oto per approximately 60-70 liters. After observing the algae in your tank for a week you will get the answer for whether or not you need to add more Otos or if they have sufficient algae. Keep a close eye on their stomachs: round bellies are a good sign of algae sufficiency. It is good not to clean all your aquarium glass at once since they will eat the algae off the glass. Otos should be kept with smaller/calmer fish. They like to rest on broad plant leaves and bogwood rather than gravel.

Otos can be difficult to acclimate to the home aquarium, but if provided with correct water conditions and there is some green food they will be fine. The setup should be well established with a sand or gravel substrate, and densely planted with live plants. An established algal growth is essential. While they will take flake food and sinking pellets the natural greens are needed to provide proper health. If no algae is available they will eat soem softer bodied plants. Provide good water circulation and filtering. Best to keep in groups. The actual number will vary upon the tank size. Compatible with most fish except the larger predatory species. Otos live up to 5 years. They need a pH around 7. Water temperature should be around 25C. More info about Oto Catfish can be found in the Gallery section.

Malaysian Trumpet Snail 4. Malaysian Trumpet Snail
Melanoides tuberculata grows not longer than 2 cm and is the best snail addition to a planted tank, especially! They will eat algae, dead plant material, leftover food and will not eat your plants. The main reason they are kept in planted tanks is for their ability to aerate the gravel since they spend most of their time digging through the substrate. They will come out of the gravel at night. If you are concerned that your snails are gone or dead, try to focus on the gravel surface for a while and you will see at certain places that your gravel is moving. That's the snail digging its way through. All snails need alkaline waters to rebuild their shells. Loaches and Cichlids will eat snails. This snail is a good indicator for poor water quality. If something is wrong they will all head up towards the surface over the aquarium glass. More info about Malaysian Trumpet Snails can be found in the Gallery section.

Bristlenose Pleco 5. Bristlenose Plecos
One of the most popular and readily available algae eaters, they belong to a group of suckermouth catfish species (Ancistrus spp.) that often have curious growths around their head/nose and grow to 10-15 cm. They need constant supply of green foods. It is good to feed them with blanched vegetables and sinking algae tablets. Live plants are not beneficial. Even though, in general, they will not harm plants, it's been known that in case of insufficient green foods they will eat Amazon swords and other softer leaved plants. These fish are nocturnal and need shelters and dark substrate to feel safe. Bristlenose plecos are known to be peaceful and compatible with many fish except the predatory ones. The water should be well oxygenated with a moderate current. More info about Bristlenose Catfish can be found in the Gallery section.

Ramshorn Snail 6. Ramshorn Snails
These snails (Planorbis spp.) are a good addition to planted tanks, since they will not attack plants. It's been known though that in situations where no other food is available, they will munch on Hygrophila spp. and similar plants. These snails grow to 2 cm. Ramshorn can be red or brown. Their main diet is based on algae that coats the plants, aquarium glass and decorations. They will also eat dead plant material, food leftovers and fish eggs. The larger Colombian Ramshorn is a good idea for a non-planted tank overrun with algae, but in planted tanks will feed on plants. All snails will do better in harder, alkaline waters since their shells tend to dissolve in acidic waters that lack calcium. Snails will get eaten by most Loaches and Cichlids. More info about Ramshorn Snails can be found in the Gallery section.

Nerite Snail 7. Nerite Snails
These snails (Neritina spp.) are among the most beautiful available in the aquarium trade these days. It is not just the beauty of their shell patterns that makes them so desirable, but also their appetite for algae. It is known that Zebra Neritinas eat the hard to clean Green Spot algae and the carpet-like Green Beard algae. These snails will not do well for long in pH lower than 7 since they need alkaline and hard water conditions to keep their shells healthy. When reproducing they will often spread hundreds of hard white eggs all over the decoration and equipment, which can be difficult to remove. Loaches and Cichlids will eat these snails. They grows to about 3 cm. Cover the tank, since Neritinas are known for their ability to leave the tank. More info about Zebra Nerite Snails can be found in the Gallery section.

Twig Catfish 8. Twig Catfish
also known as Whiptail Catfish, these are several species of unusual, thin suckermouth catfish (Farlowella spp., Rhineloricaria spp.) that grow to about 10-20 cm. If you have a well established, at least 70 liters, planted tank with aged water, lots of bogwood and small, peaceful fish like Rasboras, Tetras, Hatchets and Pencil fish you can feel free to add this strange looking algae eater to your fish family. Its main diet is based on algae. It should be fed at least twice a week with spirulina/algae tablets. This catfish should not be kept with aggressive fish like Barbs or Cichlids since it is very fragile. It's been known that Farlowella doesn't respond well to large water changes so few smaller changes in a week are recommended. More info about Twig Catfish can be found in the Gallery section.

Common Pleco 9. Common Plecos
Common Plecos are a mix of Loricariidae suckermouth catfish species (Hypostomus spp., Liposarcus spp.) which grow to sizes typically between 30 and 60 cm, so they are an option only for very large tanks (300 liters and up), with other large fish. Most of them have a large tolerance range for pH and temperature. Include some driftwood for them to use as a resting place and retreat. They are nocturnal so it is usually best to feed them at night time. They are omnivorous and do eat algae, but also accept small live or frozen foods, green foods such as lettuce and peas, cucumbers, plus vegetable-based flake foods. As they grow they begin requiring a serious amount of daily food, more than most tanks can provide with just algae. They are oportunistic feeders and will happily eat a live fish if it lies in their way and fits into their mouth. Also, starving specimens have been known to latch onto the sides of larger fish to try to eat their skin mucus. They can be quite destructive when moving around the tank, releasing plants and dislodging rocks with their head-butts or a swipe of their powerful tails. Plecos will often eat the plants in the aquarium as well. More info about Common Plecos can be found in the Gallery section.

Livebearers 10. Livebearers
Mollies, guppies, platies and other Poecilia or Xiphophorus are also algae eating fish, but not the best in my experience. They will bite off and eat soft hair algae and some other strand-like types of algae, but that is pretty much it, as far as I know. Since most fish will eat this type of algae I don't find it necessary to keep this fish for the specific purpose of algae eating. For example, freshwater angelfish do eat hair algae also, but it would be funny to suggest them as additions for an algae eating crew. More info about livebearer species can be found in the Gallery section.

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