What Animals Eat Seaweed?

Written by: Annemarie Dutton
Last updated on:

“Seaweed” is the common name for countless species of marine plants and algae that grow in the ocean and rivers, lakes, and other water bodies.

Some seaweed are microscopic, such as the phytoplankton, which lives suspended in the water column and provides the base for most marine food chains. Some are enormous, like the giant kelp that grow in abundant “forests” and tower-like underwater redwoods from their roots at the bottom of the sea. 

Most are medium-sized, come in colors of red, green, brown, and black, and randomly wash up on beaches and shorelines just about everywhere.

Seaweed is a vital part of the ocean’s food chain, serving as a source of food for many different kinds of animals.

In this article, we have explained different types of fish that like to eat seaweed. Please read on if you would like to know:  “What animals eat seaweed?”

What is Seaweed?

Seaweed is a plantlike structure consisting of green, brown, and red microalgae due to pigment.  These microscopic organisms provide the source of the food chain.  

Seaweed is like plants that grow in bodies of water such as rivers, oceans, and lakes in different ecosystems. Seaweed produces oxygen for other species and gives a nutritious diet to aquatic organisms.  

Can Animals Eat Seaweed?

Seaweed is a valuable food source for sea animals that eat algae. It is beneficial for both freshwater and saltwater fish. Crustaceans, Fish, Sea Urchins, Seals, Sea turtles, Lobster, Crayfish, Woodlice, and many more eat Seaweed. 

Why Do Animals Eat Seaweed?

The seaweed’s job is to give nutrients and energy to animals. It is full of minerals, vitamins, fiber, and protein with essential amino acids. Beds of seaweed provide shelter and habitat for scores of coastal animals during their life cycle.

Is Kelp A Seaweed?

Kelp is large, brown seaweed that grows in shallow, nutrient-rich saltwater near coastal regions worldwide. It differs slightly in flavor, color, and nutrient profile from the type you might see in a sushi roll.  Kelp also produces a compound called sodium alginate.  

What Kind Of Fish Eat Seaweed?

Herbivorous fish eat seaweed, but Omnivorous fish eat seaweed and animals too. Other types of fish can eat seaweed unintentionally when hunting their prey or as part of their health routine. 

Some fish eat seaweed not just because they like the taste but to help their digestive system. 

Freshwater Fish That Eat Seaweed

As you might know, hundreds of thousands of different fish are found in freshwater.  We decided only to name a few species that you might have in your household aquarium.  

Examples of freshwater fish that feed on seaweed include:

Angel Fish

Angelfish members of the Pomacanthidae family are omnivores that feed on marine plants and animals, but many species lean towards being more herbivorous. While many prefer to eat macro and filamentous algae, others prefer microalgae or diatoms. These fish are constant nibblers and grazers.

Goldfish

Goldfish have no stomachs; they are constantly on the lookout for food. Goldfish will eat algae and seaweed wherever they find it – off the sides of your tank, off decorations and plants, and off the gravel on the bottom of your tank.

Neon Tetras

As omnivores, Neon Tetras will eat some algae. They will nibble on algae which may help control the algae growing in your aquarium.

Koi Fish

Koi are naturally omnivorous, which means they’ll eat anything from algae and plants to bugs and even small fish.

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Mollies

Some omnivores like Mollies & Rainbowfish require more vegetation in their diet than other fish species. 

Pleco

A pleco’s diet should consist of algae and sinking algae wafers primarily. You can also supplement with blanched vegetables once per week. Depending on the pleco species, you also need to provide driftwood for them to rasp on to help digest their food.

Saltwater Fish That Eat Seaweed

There are hundreds of thousands of saltwater fish that eat seaweed.

Clownfish

Clownfish are considered omnivores because they can eat both algae and flesh, which helps to make feeding them a simpler task. A typical Clownfish diet can consist of fish eggs, larvae, copepods, algae, worms, and small crustaceans.

Pacific Blue Tang

The Pacific blue tang is an omnivore. It primarily eats plankton, algae, seaweed, or kelp in the wild, but in aquariums, it also eats bloodworms, shrimp, and other seafood.

Surgeon Fish

Convict surgeonfish (Acanthurus triostegus) are the roaming sheep of the reef, but instead of eating grass, they feed on algae. Their grazing helps balance the growth of algae and coral on the reef. Both corals and algae get their food from sunlight, but there is limited space underwater where sunlight reaches.

Benefits Of Seaweed For Fish

Seaweed grows naturally in the water, and you can also harvest it for your aquarium fish. It is suitable for marine and tropical fish species.

Seaweed is the best source of natural elements like minerals, vitamins, and other nutrients. It contains various essential anti-oxidants that enhance the immune system and have anti-inflammatory advantages.

It is fibrous, which improves their digestion because they have a very delicate digestive system. These veggies improve the water quality in the aquarium, farm, and ocean bottom. They are also a good source of minerals and vitamins.

Is Dried Seaweed Good For Fish?

Yes, dried seaweed is good for fish.  

I bet you love sushi. Nori is a natural seaweed that is roasted or dried, and believe it or not, it is used as human food in oriental kitchens. When aquarium specialists found the health benefit of Nori, which was high in protein, vitamins, carbohydrates, and especially minerals, they began using it for their aquarium fish.

It is ideal for feeding surgeonfish, angelfish, celeste fish, and many other types of algae eaters such as hermit crabs and snails.

Do Starfish Eat Seaweed?

Starfish love to eat a variety of plant matter they find in the sea and ocean. They eat coral polyps, seaweed, kelp, seagrass, red algae, plankton, and various other types of plant matter. 

If starfish cannot get live plants to consume, they will also feed on decomposed plant matter that they find on the ocean floor.

Do Shrimps Eat Seaweed?

Shrimp are excellent pets that can live in freshwater and saltwater, and there is a wide variety of shrimp. We recommend getting one for your aquarium if you don’t already have one.

Shrimps are very helpful for the maintenance of any aquarium. They eat all the filamentous algae born inside aquariums, keeping them free of algae, although they don’t eat black algae.

They also feed on larvae, but their favorite plants are Riccia.

The Riccia fluitans aquatic plant is a form of moss occurring naturally on all continents. The plant is commonly used to define landscape shapes in high-end display tanks. Due to this increasing popularity, Riccia is becoming a common plant in aquariums.

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Do Turtles Eat Seaweed?

Turtles do not have teeth but use the sharp edges of their mouth to cut food; for this reason, the feeding of turtles is based on plants and marine invertebrates.

Turtles have a similar condition as fish. We can classify them into these three categories: carnivorous, herbivorous, and omnivorous.

 Herbivorous turtles consume seaweed and marine phanerogamic plants like Zoostera or Posidonia.

Can Birds Eat Seaweed?

One bird-safe food that is rich in iodine is seaweed. … Kelp is considered a “super-food” because it packs massive amounts of nutrients into a small package! Just a tiny pinch a few times a week offers enormous benefits.

Parrots

Parrots can eat seaweed, and in fact, it can be beneficial for them in small amounts. Since seaweed is filled with so many nutrients and is harmless for parrots, it can be a good source of iodine. 

Crows

A wide range of marine mammals inhabit kelp forests for protection and food.  Kelp forests are a natural buffet for birds such as crows, warblers, starlings, and black phoebes that feed on flies, larvae, and small crustaceans abundant in kelp forests.

Can Humans Eat Seaweed?

Eating fresh seaweed is generally considered safe for most people and is mainly consumed when eating sushi. While the plant offers many health benefits, there are a few things to watch out for:

Too much iodine. While iodine is a vital trace mineral for thyroid health, too much can have the opposite effect. 

It may interfere with certain medications. Seaweed contains a high amount of potassium, which can be harmful to individuals with kidney disease. Seaweed also contains vitamin K which could interfere with blood-thinning medications such as Warfarin. 

Some varieties of seaweed may contain high levels of arsenic, cadmium, mercury, or lead, depending upon how they’re grown. Some types may have high levels of heavy metals. The FDA regulates the heavy metals in fresh seaweed, but not supplements. 

Wrapping Up

Many invertebrates eat seaweed, such as jellyfish, crabs, crustaceans, sea urchins, seals, sea turtles, lobster, crawfish, and woodlice, to name a few.  Fish such as the butterfish have bacteria in their gut and can eat and digest seaweed.

Contrary to what we believe, seaweed is not a plant. Although it looks like one, it does not have roots like a plant.  Seaweed is also known as sea algae and grows in oceans, lakes, and rivers.

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