Best Algae Eaters For Outdoor Ponds {A Top 5 List and a Bonus}

Are you looking to stock your pond with algae eating fish? Did you know that if you choose the wrong algae eaters for the wrong type of algae, they won’t eat it? Being stuck with hungry algae eaters and a pond full of algae would be a nightmare.

It this article, we’ll make sure to list the best algae eaters for your pond.

Best Algae Eaters For Outdoor Ponds. Your pond size and temperature affects the decisions you make for the right type of algae eaters suitable under those conditions. There are plenty of options we will list for you, but you must measure your pond and test your water parameters including temperature to make the right choices. 

How Do I Control Algae In A Pond?

You have four main options for controlling algae in your pond:

  • Chemical Algaecide
  • Plants That Provide Shade
  • Clean Up More Often
  • Algae Eating Fish


A large pond or a neglected pond that has an overgrowth of algae might need a treatment of algaecide right away. Being proactive for a pond that doesn’t have too much algae in it means you don’t have to resort to chemicals right now.


Stock your pond with plants that can provide shade to prevent the direct sunlight from igniting algae overgrowth. Submerged plants add more oxygen. Other plants help release natural peroxides in the water to clear up algae. Certain plants act as blockers from direct sunlight. Here are our favorites:

  • water lilies
  • lotus
  • barley straw
  • water lettuce

Clean Up

Debris and ammonia builds up when fallen leaves, plant material or leftover food get out of hand. Maintain your pond’s clean and clear water by scooping up debris more often before they encourage the growth of algae and stress your fish.

Algae Eating Fish

Algae eating fish enjoy eating:

  • green algae
  • carpet algae
  • hair string algae

Blue-green algae or planktonic algae contain cyanobacteria that fish find toxic or distasteful. They will not feed on these particular types. Nevertheless, algae eaters are our hands-on assistants helping us maintain and balance our pond’s ecosystem. They should be included in everyone’s pond that is built to inhabit fish.

How Do I Choose the Right Algae Eaters?

This is the important part of the decision making process to keep your pond clean and clear of algae. How big is your pond? Some of the fish we can recommend will grow very large and your pond might not be equipped to handle to size of some species of carp, for example.

Another factor is the temperature of the water. If the climate in your area is routinely hot or above 70°F, then certain algae eaters will become stressed or sluggish and refuse to eat the algae under hotter conditions. Measure your pond and take stock of the temperature year round while comparing that to the fish you choose.

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Our Top 5 Algae Eaters

  1. Koi Fish
  2. Channel Catfish
  3. Pond Loach
  4. Flying Fox
  5. Shubunkin Goldfish

Koi Fish

If you have over 1000 gallons of water capacity in your pond and temperatures of 60-70°F for most of the year, koi would be a great option. Remember that they grow around 12-15 inches. They are hardy will feed on algae in the winter months too when temperatures dip where they tend to mostly hibernate.

They will wake up from their slumber from time to time to dig up some algae at the bottom of the pond. You can also try to hand feed some algae to koi. Start by mixing algae with protein rich food sources that they love to get them used to the algae. Soon after, they will start grazing on it without your involvement.

Channel Catfish

These fish get big. An average size of 15-24 inches means that your pond should be able to hold over 1000 gallons of water to support these incredible algae eaters. They are bottom feeders with a big appetite to scoop up algae and other crustaceans.

Channel catfish are not the best pondmates because they are aggressive and will push around other fish to get most of the food being offered in the pond.

Pond Loach

A pond loach can survive in cooler temperatures. You can keep your pond loach in weather under 50°F, but use a deicer in the coldest months to keep them alive as they munch on the algae all year round.

They are good neighbors with koi or goldfish because they aren’t very aggressive. Some may grow up to 12 inches, but they’ll keep to themselves and make the algae their primary food in your pond.

Flying Fox

The flying fox is a small fish that grows up to 6 inches, but they dart around the pond furiously. They require more pond aeration and love nibbling on those hard to reach patches of algae in your pond. Slower moving fish may not enjoy swimming near these zippy fish. Flying fox fish are great for smaller ponds at 30 gallons or larger.

Shubunkin Goldfish

We picked this fish in particular because its beautiful and hardy. They are small enough to thrive in many ponds, but sometimes they’ll grow up to 12 inches. They can tolerate cold water and get along with other fish quite well in your pond all while using their ferocious appetite to devour green algae.

A Bonus Algae Eater! The Trapdoor Snail

We added a sixth option that didn’t make our top five list because the trapdoor snail may not have been on your mind when considering algae eating fish. These little snails enjoy soft algae growing on plants without harming the plants.

They can also help with leftover food and debris at the bottom of the pond. Try not to overstock your pond with too many trapdoor snails because they also release a lot of waste from their consumption of algae. Too much waste will lead to more algae growth.


Include algae eaters on your pond maintenance team, but remember that you’re the captain of the algae clean up crew. You can include plants and algaecide, but your personal effort to maintain and clean your pond actively along with algae eaters will ensure that the balanced ecosystem will not get out of hand by an overgrowth of algae.

Brian Arial

Brian Arial has kept fish for leisure and worked with fish stores for most of his life. He enjoys writing and caring for aquariums and ponds.

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