If algae is growing all over your aquarium, you need some hungry helpers to curb the spread. This list of the top 10 most amazing algae eaters includes animals that are safe for aquatic plants and often work together to get more done.
Aquarium Co-Op has sold a lot of live plants. One of our main goals is to keep the plants as free of algae as possible. That’s why we utilize the most effective algae eaters in the aquarium hobby for our holding tanks. We’ve learned that each algae eater has a mouth and body shape that makes it best for eating certain kinds of algae. So, to get rid of all the different kinds of algae that might show up, we mix different kinds of algae eaters in our aquariums. If your tank is very big, start with just a few of these algae eaters. Then, change the lighting and plant food in the tank and wait a month to see how they do against the algae. If you need additional help, consider getting more clean-up critters from this list.
Algae growth is a common nuisance in home aquariums. The slimy green stuff often coats tank walls decorations, and plants much to the chagrin of fishkeepers trying to maintain ideal water conditions.
While unsightly and often detrimental in excess, algae do play an important role in the aquarium ecosystem. Algae help stabilize water parameters by producing oxygen and absorbing carbon dioxide and ammonia produced by fish, plants, and bacteria. Algae also provide food, shelter, and breeding sites for various microorganisms and invertebrates.
Some fish will naturally consume certain types of algae as part of their diet. Understanding which fish eat algae, the types of algae they prefer, and how to supplement their nutritional needs can help you effectively control algae while keeping your fish happy and healthy.
Do Fish Eat Algae?
Many species of fish are opportunistic omnivores and will eat algae in addition to other types of foods. Scarping algae from surfaces provides fish with extra nutrition and satisfies natural grazing behaviors.
Certain groups of fish have mouth shapes and digestive systems adapted specifically for eating algae, including:
-
Catfish – Like plecos and otocinclus that use suckermouths to rasp algae off surfaces
-
Shrimp – Such as amano and cherry shrimp that pick at hair algae and detritus.
-
Snails – Nerites and mystery snails scrape green spot algae and diatoms.
-
Specialized algae grazers – Siamese algae eaters American flagfish mollies.
While most fish consume some algae, levels are often limited. Algae alone is not sufficiently nutritious to sustain fish. Feeding nutritionally balanced prepared fish foods is essential for health. Supplying a variety of foods also prevents selective feeding of only preferred algae types.
Why Do Fish Eat Algae?
Fish eat algae for several reasons:
-
Natural grazing behavior – Many fish continually forage for food. Picking at algae satisfies instinctive grazing habits.
-
Supplemental nutrition – Algae provide fish with proteins, carbohydrates, vitamins, minerals and fiber. However, nutritional value depends heavily on the type of algae.
-
Gut health – The indigestible components of algae can act as a laxative and aid digestion. Algae help maintain regular bowel movements and prevent intestinal blockages.
-
Hide tasty microfauna – Algae harbor microscopic animals like daphnia and copepods that fish prize as high-value protein and fat sources. Fish often scrape algae to access these nutritious treats.
While algae benefit fish in moderation, excess growth causes problems including:
- Reduced oxygen and increased CO2 levels
- Physical damage to gills and skin
- Competition with plants for nutrients and light
- Clogged filters and pumps leading to equipment failure
Controlling algae helps maintain a healthy aquarium environment. Certain fish can be used selectively to graze down nuisance algae without damaging aquarium plants.
What Types of Algae Can Fish Eat?
Fish consume many different freshwater algae types including green algae, diatoms, blue-green algae and red algae. Preferred species depend on the type of fish and its mouth shape and digestive system.
Green algae – Common in aquariums. Seen as a light dusting, spots or furry tufts. Fish like American flagfish and mollies graze well on green algae like spirogyra, oedogonium and cladophora.
Diatoms – Microscopic, unicellular, golden-brown algae. Coat surfaces in a brown film. Eaten by otocinclus, nerite snails and shrimp.
Blue-green algae – Also called cyanobacteria. Potentially toxic. Only consumed by some specialized fish like tilapia.
Red algae – Encrusting species like black beard algae and staghorn algae. Selective grazers include Siamese algae eaters and Florida flagfish.
While technically algae, plants like duckweed, elodea, and anacharis are not normally consumed by fish. Only certain specialized herbivores will eat higher aquatic plants.
Hair algae, black beard algae and green spot algae are especially difficult to eradicate manually. Using fish and inverts to selectively graze these stubborn forms of algae can be an effective part of an overall tank maintenance plan.
Best Fish for Eating Algae
Some of the top fish for munching different types of aquarium algae include:
Green Algae Grazers
-
Rosy barbs – Active schooling fish. Peaceful when kept in groups.
-
Clown plecos – Small colorful suckermouth catfish. Peaceful.
-
Mollies – Livebearers that come in many colors. Brackish water species.
-
Tilapia – Cichlids that do well in warmer tanks. Can eat blue-green algae.
Diatom Eaters
-
Otocinclus catfish – Peaceful dwarfs with specialized mouthparts for eating diatoms. Sensitive water parameters.
-
Nerite snails – Good for green spot algae. Cannot reproduce in freshwater.
-
Amano shrimp – Active little shrimp that readily eat many hair algae types.
Red Algae (Brush Algae) Eaters
-
Siamese algae eaters – Active fish that graze well on red algae. Can show aggression.
-
Redline shrimp – Small colorful shrimp that pick at difficult red algae.
-
Florida flagfish – Hardy fish with big appetites for red algae. May eat plants.
Fish That Should Not Eat Algae
While many fish consume some algae, there are certain species that should avoid it including:
-
Bettas – Insectivores unsuited for digesting plants. Prone to constipation.
-
Goldfish – Messy eaters that produce ample waste. Better off with pellet foods.
-
Cichlids – Prefer higher protein foods like brine shrimp and bloodworms.
-
Wild caught fish – Require specific diets. Algae may cause malnutrition.
-
Carnivores – Discus, angelfish, cichlids, puffers. Need high protein and fat.
-
Herbivores – Silver dollars, clown loaches. Graze aquatic plants, not algae.
-
Fry and juvenile fish – Need highly nutritious prepared foods to grow.
While most fish benefit from some supplemental algae grazing, levels should be limited to prevent nutrient deficiencies.
How to Supplement Algae-Eating Fish
When housing algae-eating fish, their diet still requires nutrient-rich preparations as the main food source. Follow these tips:
-
Offer a high quality staple pellet daily with adequate protein and vitamins. Feed several small meals per day.
-
Augment with treats like brine shrimp, blood worms, baby shrimp, plankton and vegetables for variety.
-
Maintain algae growth to supplement, but not to excess. Spot clean thick algae as needed.
-
Presoak foods for delicate fish like otocinclus that may have trouble competing for foods.
-
Avoid overfeeding to encourage algae consumption. Monitor fish body condition.
-
Supplement foods for grazers like shrimp and snails with calcium, minerals and spirulina.
With a little effort maintaining their environment, algae-eating fish can help control excessive algae growth. But their nutritional needs must still be met through proper feeding and supplementation to remain healthy. Allowing fish to eat some algae creates a more natural ecosystem and enriches their care.
Siamese Algae Eater
This is a 6-inch (15 cm) cleaner fish called Crossocheilus oblongus, or SAE for short. It is usually kept in bigger aquariums. They can eat hair algae, black beard algae, and scraps from the fish tank because their mouths are turned down. There is evidence that SAEs eat more algae when they are young because adults in the aquarium get most of the food. So, you might need to cut down on food portions to get older SAEs interested in eating algae again. Like hillstream loaches, SAEs can be territorial with their own species or species that look a lot like them, so get at least three of them together to get more algae-eating power.
There is a difference between Siamese algae eaters and Chinese algae eaters. Chinese algae eaters are much meaner and can grow twice as big.
In males, Jordanella floridae has beautiful red stripes and a rectangular patch on its shoulder that looks like the US flag. This fish is also called the American flagfish. This 2. Voracious algae eater is 5 inches (6 cm) long and has a mouth that is perfect for ripping out hair algae, black beard algae, and other fuzzy algae. However, it can damage more delicate plant leaves when it does this. This killer fish might be the right one for you if you have an unheated tank with other fish that swim quickly.
As a native of North America, flagfish can thrive in cooler water environments without any aquarium heaters.
One of the best known algae eaters is the Plecostomus. However, they get very big as adults and aren’t good for a typical home aquarium. Bristlenose plecos are peaceful catfish in the genus Ancistrus. They stay between 4 and 5 inches (less than 13 cm) long, which means they can live in a 25-gallon tank or bigger. Their suckermouths are made for devouring algae, vacuuming up food crumbs, and keeping driftwood clean. But make sure you give them a variety of foods, like sinking wafers, frozen bloodworms, and Repashy gel food, to make sure they get all the nutrients they need.
Males are known for the bristles on their snout, whereas females have a more clean-shaven face.
Mollies are well-known livebearers in the genus Poecilia. They live in 100% fresh to 100% salt water in the Americas. Because their stomachs are empty and their jaws are flat and grasping, they are always picking at algae that is on plants, hardscape, and even flat surfaces. People who keep fish in aquariums have selectively bred them to have many different colors, patterns, body shapes, and fin types. They can easily have babies if they are given lots of food and places to hide them. Just so you know, fancy mollies are often raised in fish farms with salty water. If you think your new fish might be sick, you might want to add aquarium salt and extra minerals to help them do well.
Mallies come in a wide range of sizes, from the tiny balloon molly (2 inches/5 cm) to the huge sailfin molly (15 cm).
Some barbs, like the rosy barb (Pethia conchonius), like hair, staghorn, and thread algae, which are fuzzy. This relatively peaceful species grows to 3 inches (7. 6 cm) long and comes in normal, neon, and long-finned varieties. Similar to the flagfish, rosy barbs can be kept in unheated aquariums with other speedy tank mates. Keep them in groups of at least 6 to 10 (with more females than males if possible) in a 29-gallon tank or bigger to keep them from getting aggressive.
Pethia conchonius aren’t as aggressive as most barbs. They won’t bother your other fish as long as you have a good-sized school to keep them busy.
Want to learn more about how to get rid of algae? Read our full article on the most common types of algae found in freshwater aquariums and how to get rid of them.
Reticulated Hillstream Loach
This oddball fish is one of the coolest-looking algae eaters you will ever see. Growing up to 3 inches (7. 6 cm) in size, it looks like a miniature stingray covered with golden-brown dots and intricate black stripes. They can easily clean large, flat surfaces like aquarium walls, rocks, and broad plant leaves because they have strong grips. Think of them like your personal window washers for diatoms and other flat kinds of algae.
Because they can be territorial, it’s best to have either just one loach or at least three of them together to keep the fighting in check. Keep them in water that is cooler and has a stable pH level, and feed them good sinking food like Repashy gel food. You might see some baby loaches appear in your aquarium.
There are many species of hillstream and brook loaches, such as Sewellia lineolata, Beaufortia kweichowensis, and Gastromyzon ctenocephalus.
Hillstream loaches are great at eating flat algae, but you might also need an algae eater with more flexible fingers that can get into tight spaces or tear off pieces of fuzzy algae. Meet Caridina multidentata, a clear-brown dwarf shrimp that can reach 2 inches (5 cm) in length. They are one of the few animals that will eat hair algae and black beard algae, but only if you don’t give them too much food. Because they are so small, you’ll need at least four of them (or even more) to really slow down the algae growth. For more details on their care requirements, read the full species profile here.
Even though amano shrimp can breed in aquariums, you won’t get any babies unless the shrimp are raised in saltwater.
There are a lot of different kinds of small snails in the Neritidae family. They are used as decorations and are good at both scavenging and eating algae. They work great for getting rid of tough green spot algae and other types of algae that grow on plants, driftwood, and home decor. There won’t be an overpopulation of these white eggs that look like sesame seeds in fresh water like there is with most other types of aquarium snails. While there are many beautiful varieties to choose from (e. g. , tiger, zebra, horned, and red racer), but we like olive nerite snails the most because they seem to be the toughest. Don’t forget to add extra calcium to the water (with crushed coral or Wonder Shell) and the food they eat (with nano food blocks) to help their shells grow in properly.
Green spot algae is hard to get off of rocks and plants, but nerite snails are one of the few animals that can do it and eat it.
A single cherry shrimp (Neocaridina davidi) isn’t as good at eating algae as an amano shrimp if you put them side by side. But these brightly colored dwarf shrimp are easy to breed in home aquariums, and once you have a good-sized colony, they’re great for keeping food and algae from building up. Their tiny legs help them dig through the substrate, plant roots, and other small spaces, and they’ll eat anything that can be broken down. At 1. Cherry shrimp are about 4 inches (11 cm) long and come in almost every color of the rainbow. You can easily sell them to a fish store or other hobbyists for a profit. Read more about them in our cherry shrimp article.
It’s beautiful to see a huge group of bright red cherry shrimp exploring a lush forest of green aquarium plants.
Catfish in the genus Otocinclus are often called otos or dwarf suckermouths because they only get about 2 inches (5 cm) long. Their smaller, slender bodies allow them to fit into tighter spaces than other algae-eating fish. Like the hillstream loach, their mouths are made to eat diatom algae from flat surfaces. You can usually find them sitting on aquarium glass or plant leaves. Otos often don’t get enough food, so make sure you give them a lot of Repashy Soilent Green and vegetables like green beans in a can and zucchini slices that have been blanched. For more information on how to care for these adorable catfish, read our full article here.
Because otocinclus catfish like to swim in groups, get at least three to six of the same species to make these shy fish feel safe and at ease.