The diet of guppies consists of various meals such as live foods, plants, vegetables, and meat products. Since algae is a problem in many tanks, you must wonder whether guppies feed on it.

Guppies are omnivores and graze on algae, especially the soft green algae found in aquariums and their natural habitats. Their natural diet consists of both plant and animal matter, including algae, insect larvae, and tiny crustaceans.

Do guppies eat algae

However, guppies don’t like mature and tough algae such as black beard algae. They’ll enjoy algae with soft textures, such as green algae or brown algae. 

In this article, you will learn the types of algae that guppies can eat, how long the fish can survive on algae, and what else you can feed them.

Types of algae that guppies can eat

Algae grows naturally in freshwater tanks and reach its peak growth in four weeks. Therefore, clean your tank weekly or use biological algae control mechanisms like introducing fish like Bristlenose plecostomus and twig catfish that eat algae. Water lettuce can also help you control algae in your aquarium.

Guppies cannot control algae in your fish tank because they feed on a tiny portion of algae. I’d recommend that you feed your guppies a balanced diet for them to grow healthy and happy in the aquarium.

Here are the types of algae that guppies commonly feed on:

Staghorn algae

Staghorn algae grow like the horns of a stag. It is one of the algae that guppies can eat. Staghorn algae belong to the red algae group, which comes in various shades of grey.

Grey staghorn algae
Staghorn algae

It grows in water with poor oxygen circulation. However, some people use it to decorate their aquariums.

To know what kind of algae you’re dealing with, remove some and put them in alcohol. If the algae turn reddish, it is a staghorn alga.

The algae are usually very challenging to remove. It requires thorough cleaning in the aquarium. 

Nevertheless, guppies eat just a tiny portion of it. That means you will need algae eaters or other control methods to remove staghorn algae from your aquarium.

Black beard algae

Black beard algae also called brush algae, belongs to the red algae group, just like staghorn. The algae’s color varies from green to gray and sometimes deep black, depending on the environment. 

Guppies love feeding on black beard algae but do not rely entirely on the algae as their main diet.

Blackbeard algae depend on the water quality inside the aquarium for photosynthesis. They grow very fast, so relying on your guppies to control their growth might not work.

If your fish tank has black beard algae, clean your tank weekly to regulate its growth. Adult guppies feed on a small portion, but the fry does not eat the algae. Keeping larger fish that eat algae together with your guppies can control the growth of black beard algae.

Brown algae

Brown algae is a major seaweed in a large group of multicellular algae and are common in new aquariums. Guppies feed on brown algae because the algae are smooth and soft.  

Unlike black beard algae and staghorn algae, brown algae is a nightmare for aquarists. The algae thrive in low CO2 water and use the by-products of fish waste such as nitrates and nitrites for photosynthesis.  

That means brown algae are constantly feeding. Therefore, brown algae proliferate the fish tank. To control the algae’s growth, eliminate all the nutrients necessary for their survival in the tank. Change 20% to 50% of the water every week or two.

Fuzz algae

Guppies are attracted to fuzz algae because the algae are short and a vibrant green color. 

However, fuzz algae grow mostly in new fish tanks and aquariums with chemical imbalances.

It’s easy to control fuzz algae because when the water chemicals are balanced, nothing will be left for them to thrive on. 

To attain a stable chemical balance in your fish tank, feed your guppies less and clean up after them to remove food leftovers. You might also want to use a good aquarium test kit to keep the water clean and healthy.

Green water algae

Green water algae are the most common algae in aquariums and can be difficult to eliminate. Even if you change a lot of the water, green algae grow back in three days.

Although it is stressful, green water algae are not toxic, so guppies occasionally eat it. The green water algae overgrow in tanks receiving more sunlight and accumulating a lot of toxins such as nitrates, nitrites, and ammonia. 

Guppies feed on green algae because of their soft texture, but the fish will not eat much of it. You must control its growth to avoid stressing and suffocating your guppies.

Blanket weed algae

The blanket weed algae, commonly known as silkweed, resembles duckweed. They do not have leaves and stems.

You can distinguish blanket weed algae by smelling it. The algae have a distinct lousy smell that’s difficult to withstand.

An aquarium with high light exposure and enough nutrients accelerates its growth. The blanket weed algae form clumps of thick green hair-like accumulation at the top of the tank.

It’s the most challenging alga to remove, and touching it can disrupt the entire tank’s optimal conditions.

Can you keep an algae eater with guppies?

When choosing tankmates for fish, there is a wide range of choices from species to subspecies of different fish categories. Finding tankmates isn’t hard for the fish hobbyists as aquarists have already determined the tankmates for different kinds of fish. So, can you keep an algae eater with guppies?

You can keep an algae eater with guppies, and they should get along very well. An algae eater such as betta fish can live with guppies provided their optimum living conditions are provided.

Both guppies and bettas are omnivores, but they have different feeding behavior. Guppies are top tank feeders while Siamese are bottom tank feeders.

When food is presented to them, guppies will snatch and eat when the food is still at the top of the tank. They might follow while still sinking, then leave when the food reaches the bottom of the tank.

Siamese will feed on the food at the bottom of the tank and any leftovers by the guppies that sank to the bottom. As algae feeders, siamese fish will eat algae whenever they are hungry, but guppies will only feed on algae once in a while.

How long can guppies survive on algae?

Guppies enjoy eating algae that naturally grows inside their tanks. They do not eat much of it because algae have no nutritional content that guppies can rely on. 

Guppies can’t go for so long without food. Adult guppies and fry can survive for not more than 3 days without food except by feeding on algae alone. However, algae have a rapid growth that guppies cannot catch up with or control. 

Therefore, although guppies can survive on algae in an aquarium, they will not be healthy or live long. Supplement their diet with protein-based nutrition and live food such as worms. 

What else to feed guppies with

Apart from algae, guppies in an aquarium are fed with meat, live foods, and plants to balance their diet. 

Here is a list of other foods that guppies can eat apart from algae.

  • Bloodworms such as tiny red larvae and the genus Glycera
  • Fish flakes such as shrimp meal, earthworms, spirulina, and vitamins and minerals
  • Vegetables such as cucumber and kale
  • Algae wafers

More about guppies:


Petersson, M. (2018). The Algae Eater Debate. It’s Not Just a Fish.

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