Algae is nearly inevitable. Every tank, at one point or another, has experienced algae. While there are other ways to solve algae problems, like more regular tank maintenance, changing source water, and increasing water flow, sometimes these methods don’t work and a more effective cleanup crew is needed. Before adding to your livestock, always make sure that you have the correct setup and enough space to allow for your new algae-eating critter!
Keep reading to find out everything you need to know about natural algae control methods and our top 8 algae eater species!
What causes algae in your fish tank?
Though introducing an algae eater into your tank might seem like an easy solution to your algae problem, this method is not treating the problem at its root. Algae growth in an aquarium is normal and to be expected. However, it can quickly overrun a tank and cause hobbyists to become frustrated and disinterested in the hobby altogether.
There are a few reasons why you might be experiencing algae. It is important to understand the main cause of the problem before introducing additional livestock to make corrections. As always, a freshwater fish or invertebrate should never be temporarily added to the aquarium unless water parameters are stable and the system is large enough.
Poor water quality
The most common cause of algae is poor water quality, usually with an excess of phosphates or nitrates. These two nutrients are quickly uptaken by algae, usually outcompeting other desirable live plants and eventually taking over the tank. Phosphates and nitrates are usually the result of overfeeding or overcrowding, though they could also be introduced into the system by way of the source water.
First, try to cut back on your feeding. Fish don’t actually need to be fed that often and can be kept on a once-a-day schedule. Make sure to only feed as much as they can eat within 5 minutes; if there is food leftover, then you are feeding too much and need to cut back.
Next, take a realistic inventory of the fish and invertebrates in your tank. If it seems like you have a lot of fish, then you probably have too many. In general, freshwater fish should be given one gallon (3.79 L) of water per inch (2.5 cm) of fish. If your tank is overcrowded, try rehoming some fish, upgrading the tank and filtration, and increasing tank maintenance in terms of filter maintenance and water changes.
Finally, check the parameters of your source water. Tap water usually contains nitrates and phosphates, and sometimes even ammonia! While these natural nutrients might be desirable for a planted tank, if your plants cannot take up phosphate and nitrate before they become a problem, then you will either need to plant more or start mixing your water with distilled/reverse osmosis water to lower concentrations.
It is always a good idea to have water parameters in check before adding new algae eating livestock. If you do choose to add an algae eater to help solve the problem, make sure that you have enough food to give after the tank has been cleaned.
Poor water movement
Algae can also be the result of poor water movement throughout the aquarium. Though you might not overfeed, detritus can get stuck in poorly circulated areas. This can directly lead to algae taking root and thriving if left to grow.
One of the simplest solutions to this is adding additional water flow through upgraded filtration or a powerhead. However, some plants and fish can’t withstand higher currents, so it’s important to think about how to best cater to your livestock.
Another alternative would be to make small adjustments to the aquascape of your aquarium. It is best to keep some space between decorations and the wall of your aquarium so that those areas get increased flow and can be easily vacuumed if necessary.
Increasing water movement could help algae thrive, though, as more water movement will cause more nutrients to be passed by the algae. It is best to make sure that water conditions are optimal as you do not want to create an even more perfect spot for algae to thrive.
Algae needs light to survive just like all plants do. Light allows both plants and algae to undergo photosynthesis, which allows the organism to feed itself and subsequently grow. If too much light is given, then algae can grow even more.
For most aquariums, an average photoperiod of 8 hours is optimal. Too little light and the plants might start to die due to lack of food; too much light and plants and algae might start to grow too much! Some hobbyists even choose to blackout their tanks for a couple of days if they’re dealing with an especially stubborn type of algae.
It is also important to consider all the light sources that your tank is receiving. Is it getting any direct sunlight from outside? Are there other external lights around the aquarium? These can all play into the growth rate of the photosynthetic organisms in your aquarium. Direct sunlight, especially, can raise water temperatures and fuel algae growth.
One easy and inexpensive solution to excessive lighting is purchasing a timer. A timer will allow for a set photoperiod that does not accidentally get left on!
Do algae eaters clean fish tanks?
If a fish or shrimp is a true algae eater, then it will help keep your tank clean. However, just because a species likes to stay towards the bottom of the aquarium does not mean that they are algae eaters! For example, Corydoras catfish are bottom-dwellers. While you might think that means they’ll eat algae, they don’t. Corydoras catfish are more likely to snack on detritus and other food that falls from the top of the tank.
It is also important to note that some algae eaters do better than other algae eaters, especially when it comes to certain species of algae. For example, Chinese algae eater fish might eat algae when they’re juveniles but actually tend to look for meatier foods once they start to get older. Other species might avoid certain types of algae altogether, leaving you with the algae problem as well as an algae-hungry fish.
Do you need to feed your algae eater?
In general, yes you need to feed your algae eater. Even if you have a tank filled with algae, that source will eventually run out and leave your fish without something to eat. However, algae eaters will probably get enough food from the leftovers of the other fish most of the time. It won’t hurt to occasionally offer some blanched vegetables or algae wafers, though!
Why did my algae eater die?
Your algae eater could have died for a couple of reasons. If other fish have also died, it might be due to poor water quality or disease. If only algae eaters were affected, it might be due to a lack of food; always make sure that your fish has a plump belly that doesn’t look sunken.
If both algae eaters and invertebrates were affected, then it could be due to other impurities in the water. Most algae eaters are scaleless species, meaning that they are more susceptible to certain nutrients and metals; these could have entered the tank through source water or medications.
Our Top 8 Algae Eater Species
Here are some of the best algae eaters you can get for your freshwater aquarium based on the likelihood of them tackling algae problems, the required tank size, and compatibility with other freshwater species!
Snails are great algae eating option if space is limited; they help overturn the substrate, eat decaying leaves, and can even eradicate some species of algae. However, they are known to overpopulate tanks quickly and have the potential to add a lot of bioload to the system. Some of our favorite snail options are nerite snails, ramshorn snails, and mystery snails.
Nerite snails (Neritidae family)
The nerite snail is a favorite for many hobbyists since they can’t successfully reproduce in freshwater conditions. They are known to eat most species of algae and will even tackle the notorious hair algae. The nerite snail stays rather small (under an inch/2.5 cm) and can have very pretty shell colorations and patterns. Nerite snails can be kept with all community fish with no problems and fit right into nano aquariums.
Ramshorn snails (Planorbidae Family)
Ramshorn snails are a close second to nerite snails in the aquarium trade, and a common freshwater hitchhiker. They mostly prefer soft green algae types but have been known to munch on some species of brown algae as well. However, these snails can reproduce in freshwater conditions and populations will need to be monitored to ensure that they don’t overtake the system!
Ramshorn snails can also be kept with all community fish without any problems in a nano aquarium, though they might snack on shrimp eggs.
Mystery snails (Pomacea bridgesii)
If you have live plants, more than likely you will already have a mystery snail population in your aquarium! Mystery snails are one of the largest types of freshwater snails and can grow to be 2 inches (5 cm)! They come in many different colors and can survive a wide range of water parameters.
Most hobbyists find them to be a nuisance in their tank due to their size and ability to quickly reproduce and take over a system. However, mystery snails are one of the best species for regulating film algae that might cover the glass and other surfaces; they have even been known to eradicate some other nuisance algae, like hair algae.
Mystery snails can be kept with an assortment of peaceful tank mates and their larger size even makes them compatible with betta fish. Always be sure to keep an eye out for eggs and baby snails though as you will want to tackle that problem before it gets worse!
If you’re looking for something a little more exciting than snails, shrimp can be just as efficient at algae eating! There are many different types of freshwater shrimp available that can help keep your tank clean. It is important to keep in mind that while shrimp tend to stay towards the bottom of the tank, they may occasionally venture up into live plants at the surface. Some of our favorite algae eating shrimp species are Amano shrimp and cherry shrimp.
It is important to note that shrimp may need to be occasionally supplemented with other food once natural algae and/or detritus levels run low. Additional food will also help supply essential nutrients needed for successful molts.
Amano shrimp (Caridina multidentata)
Amano shrimp have great personalities and can help clean the aquarium! Amano shrimp are one of the largest dwarf shrimp species and can grow to be 2 inches (5 cm) when fully matured. These almost-transparent shrimp like to graze on algae on all surfaces of the tank. Because of their demanding algae diet, they do best in larger, established tanks (10+ gallons/37.9+ L) that have plenty of biofilm and detritus to feed on. They can be kept with an assortment of community fish and other dwarf shrimp.
Cherry shrimp (Neocaridina davidi)
Cherry shrimp are a popular choice due to their size and brilliant colors. These shrimp only reach about an inch (2.5 cm) long at their adult size and are named after their deep red bodies. Cherry shrimp can usually be found alongside Amano shrimp, foraging on the substrate, rocks, and plants of your tank for algae and other detritus. If you see your shrimp munching away at leaves, it is most likely only eating algae or decaying matter!
Cherry shrimp can be kept with an assortment of community fish and dwarf shrimp. They are especially popular as a nano species, and can successfully be kept in tanks under 5 gallons (18.9 L), though bigger is always better to ensure that there is enough natural food to sustain the population.
If you have a larger tank, Otocinclus are one of the best algae eaters available. However, they can be a pretty demanding species and will need a very established and matured tank to ensure that your fish don’t quickly run out of food; even then, you will most likely need to supplement feedings with algae wafers and blanched vegetables, like lettuce or zucchini.
Otocinclus are a schooling species and need to be kept in groups of at least 4 or more. They are relatively active and need enough surface area to graze, so they should be kept in at least a 20 gallon (75 L) aquarium. Though active, Otocinclus are peaceful fish and need to be kept with other peaceful species that won’t stress them out and cause them to hide.
Siamese algae eater (Crossocheilus oblongus)
Not to be confused with the much more aggressive Chinese algae eater (Gyrinocheilus aymonieri), Siamese algae eaters (Crossocheilus oblongus) are a much more appropriate choice for a community freshwater aquarium; also note that Siamese algae eaters are often confused with Siamese flying foxes (Crossocheilus oblongus). It is believed that the Siamese algae eater is one of the few species to touch the dreaded black beard algae.
True Siamese algae eaters can grow to be about 6 inches (15.2 cm) long and are a schooling fish. Their schools are based on a ‘pecking order,’ which means that they do best when 4 or more are kept together; in smaller numbers, weaker fish are more likely to get bullied and harassed. Because they are active schooling fish, they need at least a 30 gallon (113.6 L) fish tank.
Some hobbyists have had problems with their Siamese algae eaters being aggressive towards each other and to other fish in the tank. They are also slightly notorious for ripping up aquascapes and making a mess in the aquarium. However, as long as a decent school size is maintained and the aquarium gives enough room for them to swim, you shouldn’t have too many problems.
Otherwise, the Siamese algae eater loves to pick at algae and will avoid munching on live plants. You may need to supplement algae wafers and blanched vegetables from time to time to keep your fish thriving.
Bristlenose pleco (Ancistrus sp.)
If you don’t want a schooling algae eater, then the bristlenose pleco could be a great solitary addition. One of the best things about bristlenose plecos is that they don’t get too big like their relatives, the common pleco (Hypostomus plecostomus), and usually stay under about 5 inches (12.7 cm) when fully grown. They are usually easily identified by the soft bristles on top of their mouth and come in an assortment of colors.
Bristlenose plecos can be great algae eating fish, but cannot be sustained on just algae alone and will need to be given a source of protein. The easiest way to do this is by feeding your other fish a little extra so that some makes its way down to the bottom of the tank for your pleco to find. They may also be given other algae wafers and blanched vegetables when needed.
While these fish stay relatively small, they will need a larger aquarium to be able to freely swim and graze upon different areas. Because of this, it is recommended to keep them in at least a 30 gallon (113.6 L) aquarium or more. Though bristlenose plecos are generally peaceful fish, they can become territorial towards some other bottom-feeding species.
Algae eating fish to avoid
In general, snails, shrimp, Otocinclus, the Siamese algae eater, and the bristlenose pleco are regarded as the best algae eaters for freshwater aquariums. However, you’re most likely to come across and could be recommended a few other species, like Chinese algae eaters, common plecos, and Corydoras.
Chinese algae eater (Gyrinocheilus aymonieri)
The Chinese algae eater (Gyrinocheilus aymonieri) is often confused with the Siamese algae eater (Crossocheilus oblongus), however, they are from two completely different genera! Chinese algae eaters are usually widely available at local pet stores and recommended as good algae eaters, but the truth is that they could end up hurting the rest of the fish in your tank and many hobbyists avoid them entirely.
While Chinese algae eaters might eat a lot of algae when they’re juveniles, they have been known to suck the protective slime coat layer off of other fish. This leaves those fish susceptible to diseases and infections once they reach their mature size of 5 inches (12.7 cm) in the aquarium setting. They are also very active algae eaters and could stress out other fish just by their quick movements.
Common pleco (Hypostomus plecostomus)
One of the most signature fish of the aquarium hobby is the common pleco, but they are actually one of the hardest to successfully keep in a fish tank. Common plecos can get huge, almost 2 feet (61 cm) long, and live for a long time. Because of this, they do best in large aquariums, upwards of at least 150 gallons (567.8 L) and many hobbyists resort to housing them in ponds.
On top of that, common plecos aren’t the best algae eaters by nature. These fish are more likely to feed on detritus and leftover fish food than to tackle any type of algae in the aquarium. If you’re not prepared to keep up with the demanding diet and space requirements for this fish, then there are much better options!
Members of Corydoras are a great addition to the community freshwater aquarium, however, they are not the best algae eating fish even though they live on the substrate. Corydoras make great tank mates for many different species, but they will not eat hair algae, film algae, or any other kind of algae for that matter; these fish are scavengers and will eat anything that falls from the surface above.
Corydoras are active schooling fish that will need to be fed live, frozen, and freeze-dried foods just like the rest of the fish in your aquarium. While they will usually take algae wafers as an occasional treat, don’t expect them to swim over to the closest patch of algae and chow down!
Some of the best algae eaters are shrimp, snails, Otocinclus, Siamese algae eaters, and bristlenose plecos as most of them eat a wide range of algae and are community-friendly. However, it is important to understand why your tank is experiencing an algae problem before you purchase one of these algae-eating species; algae could be due to poor water quality, poor water movement, or excessive lighting. Algae eaters should only be introduced if this problem is solved, aquarium space allows, and supplemental feedings are guaranteed.
There are some ‘algae eating fish’ to avoid, like Chinese algae eaters, common plecos, and members of Corydoras, as these species might be aggressive, too large, or unlikely to actually eat algae. Remember, never temporarily buy an algae eating fish if you don’t have the means to house it indefinitely!
If you have any questions about algae problems, algae eaters, or have had experience with one of these species successfully eradicating algae from your tank, don’t hesitate to leave a comment below!