5 Beneficial Algae Eating Pond Inhabitants

5 Beneficial Algae Eating Pond Inhabitants

Five beneficial algae-eating pond inhabitants include tadpoles, koi and goldfish, snails, loaches, and mosquito fish. Algae eaters to be wary of include Chinese algae eaters and channel catfish.

I’ll explain the reasons why in each case. Also, note that while these pond inhabitants help keep algae under control, further action is ultimately needed in the case of a major algae bloom which eventually becomes chronic.

The need for algae control

All pond owners know how problematic algae is. Further complicating matters, there are different kinds of algae and not all of them are treated the same. The algae controlling pond inhabitants are for green and string algae. These are the two most common types.

Unfortunately, blue-green algae is an entirely different beast that can’t be controlled by the following animals. Luckily, blue-green algae blooms are rare compared to common string algae. String and green algae are what I’ll cover in this article.

Why algae is bad for your pond

All bodies of freshwater have some algae to a degree. When it’s under control, it’s hardly noticeable. In fact, some types of algae are beneficial to the ponds ecosystem. What’s unhealthy is a pond completely inundated with algae of any kind. It suffocates beneficial oxygenating plants and blocks out the sun which cannot reach the bottom of the pond’s floor.

This starts out with something that’s called an algae-bloom. It differs from a bacteria bloom which also causes cloudy water but is beneficial when it clears up. An algae bloom starts off small and only gets worse, eventually taking over the entire pond.

A healthy pond shouldn’t have more than 5 to 15% algae.

Take action against algae blooms before they begin

The best way to treat algae blooms is to avoid them in the first place. The following lists conducive conditions which start algae blooms.

  • Too many hours of sunlight and not enough shade.
  • Poor water circulation.
  • Excessive nutrients in the water.
  • Too many fish excreting high levels of ammonia in the water.

Measures you can take to prevent algae blooms

  •  Add a quality beneficial bacteria product to the water. This is usually done on a quarterly basis but follow the labels instructions because different products differ. 
  • Use a product such as Nualgi, year-round in warmer climates. It’s all-natural and doesn’t contain harmful chemicals that kill your plants or fish. Nevertheless, use the product exactly as the label describes.
  • Add the right kind of animals to your pond to help control algae.
Pond Algae | Natural Pond Lover
Common pond Algae

1. Tadpoles

I actually know some people who consider tadpoles a nuisance and they have special automatic skimmers which remove them. I simply don’t understand why anyone would remove or discourage tadpoles, toads, or frogs from a pond unless they were invasive.

Naturally occurring amphibians are highly advantageous to a healthy pond’s ecosystem. They also eat bugs, lots of them. They’re like having a free pest control service. Why would you discourage something like that? Tadpoles are also very helpful when it comes to controlling algae. They eat lots of it.

Common pond frogs | Natural Pond Lover
Tadpoles and frogs are beneficial to a ponds environment.

2. Koi and goldfish

Both koi and goldfish eat their fair share of algae. They won’t live off it exclusively, but they do graze on it regularly which helps keep it under control. Still, there’s an important point I have to make here. Don’t overstock your pond with koi or goldfish. This is a very common mistake.

Also, don’t overfeed them which is another common mistake. These factors lead to algae blooms, excessive nutrients, and the kinds of bacteria you don’t want in your pond. The general rule is one koi for every 250 gallons of water.

3. Snails

Snails eat a lot of algae, other waste and excessive nutrients in your pond. They’re an important part of a healthy ecosystem. There are, however, things you must know before adding snails to your pond. It’s best to only add snails that occur naturally in your range.

Don’t add invasive snails to your pond because they’ll probably overtake it. I know from experience. Luckily, the local raccoons took care of the issue and it’s no longer a problem. Add snails found in your local waterways. You only need to add a couple. They breed prolifically when conditions are right.

Pond snails | Natural Pond Lover
An algae-eating apple snail.

4. Plecos

Plecos, also known as the suckermouth catfish are popular and common at all pet stores. Plecos live from eating algae. While these guys are peaceful and get surprisingly large, you must bring them indoors during winter unless you live in a tropical climate like South Florida.

One option is to keep a heater in the pond during winter but is that really feasible? You’ll most likely end up keeping them inside during the cold winter months in a large fish tank. Otherwise, plecos are beneficial algae eaters that help keep it under control.

5. Mosquito fish

Every pond should have mosquito fish in their pond and it’s not because they partly feed on algae. While they indeed do their share of algae control their preferred meal is mosquitoes. Mosquito larvae don’t last long in a pond full of mosquitofish. Neither do adults. Mosquito fish are the first animal I introduce to a new pond. You only need to add a few dozen.

They’re prolific and bear live young. Sometimes people complain that they have too many mosquito fish. In this case, you can manually remove them with a net and sell them to the local pet store or add a predator to help keep populations under control.

Fish for your pond | Natural Pond Lover
A subspecies of mosquito fish eat algae.

Algae eaters to avoid or be wary of

There are some fish that you shouldn’t keep in your pond unless you have something specific in mind. The fish I’m about to describe are predatory in nature. They usually do more harm than good to a natural pond’s ecosystem.

Chinese algae eater

Avoid the Chinese algae eater like the plague. First of all, they only eat algae for a short time after birth. Once they grow (and they get big), they turn into predators wiping out other peaceful pond inhabitants. While these fish are always sold as “algae eaters” at pet stores, they’re certainly not worth the trouble or worthy of the name.

Then try fishing them out of the pond once they’re established. This is another lesson learned through personal experience. Avoid them, even for your fish tank unless you’re keeping them specifically.

Channel catfish

Channel catfish are another fish common at pet stores. When first bought, they’re tiny and cute looking perfectly peaceful and harmless. Channel catfish get big. Really big. They also fall into the same class as the Chinese algae eater only they’re even more aggressive predators. It’s best to avoid these fish, especially if you’re keeping them for algae control. There are much better options.


Algae can test your patience but with some knowledge and experience, you’ll be knocking out blooms like the professionals. Just have patience and remove all dead algae that float on the surface of your pond with a dip net. Strings of dead algae are still excess nutrients which hinder progress.

Did you have an algae problem that you solved? Tell us how you did it in the comments section below!

5 Beneficial Algae Eating Pond Inhabitants