Three Best Algae Eating Fish

At some point in the life of every aquarium, algae will grow.  It’s unavoidable.  There are many types of algae and many different methods for controlling it.  You can turn the lights off for days, buy a uv sterilizer, or scrub the glass.

But why not let a fish or invertebrate do the work for you?  You don’t have to do nearly as much work cleaning.  They are happy to have a good source of food.  And you get another awesome fish (or snail) to watch and be entertained by.

This is our list of the 3 best algae eating fish for a freshwater aquarium.

Bristlenose Plecos

Anthony C [CC BY-SA 3.0]
Anthony C [CC BY-SA 3.0]
Plecos in general are great algae eaters. Bristlenose plecos are a smaller pleco that will grow to a maximum length of about 5 inches that will chow down on some algae.  The bristlenose pleco is a catfish that can often be seen sucking on the inside of the glass, leaving clean streaks in the middle of an algae bloom.  They will eat algae, but their diet should be supplemented with algae wafers and live veggies such as cucumbers.

Bristlenose plecos should be kept in an aquarium that is at least 20 gallons.  The tank should be decorated with lots of hiding places and preferable some driftwood that the pleco will slowly eat for fiber. They can be destructive towards live plants both because they can eat through leaves and because they often dart around the tank without much regard for their surroundings.  This tends to uproot plants or damage the stems.

Otocinclus Catfish

Oto catfish are a very small sleek algae eating fish that will grow to a maximum of about 2 inches long. They have a very small mouth and a small skinny body, but consume a large amount of algae in comparison to their size.

Otos are VERY sensitive to water parameters.  They should only be added to a very established tank that has been properly cycled and stable for several months.  When selecting one at the fish store, look for one that is active and healthy looking.  Take your time and slowly acclimate them to your tank.

They are very skittish and may hide for days at a time.  They prefer to be kept in groups of 6 or more to help them feel a bit more comfortable with their surroundings.  Due to their small size, they can be kept in smaller tank.

Siamese Algae Eater

Lerdsuwa [CC-BY-SA-3.0]
Lerdsuwa [CC-BY-SA-3.0]
The Siamese Algae Eater (or SAE) is a hardy and easy to careful algae eater that will eat types of algae that other fish won’t touch.  They are particularly useful in planted tanks as they will readily eat algae off of leaves and stems while being gentle enough not to damage the plants.  They grow to about 6 inches long.  An aquarium should either have one SAE or 6+.  Due to their size, one fish is appropriate for a 30 gallon tank and a school of 6 or more should only be kept in aquariums larger than 75 gallons.

They are a peaceful fish, but shouldn’t be kept with freshwater sharks as they will fight.  Siamese algae eaters resemble rainbow sharks and red fin sharks and that will incite aggression.

Note that Chinese Algae Eaters are sometimes sold as Siamese Algae Eaters.  THEY ARE DIFFERENT FISH.  Chinese algae eaters only eat algae when they are young and will grow into aggression.  Be sure to do your research before buying one in a fish store.