Do Fish Eat Seaweed? | Freshwater and Saltwater

For any fish, feeding is one of the main daily activities and for the owner one of the many joys of keeping fish in a home aquarium. Fish are vertebrate animals; they spend more time and energy searching for food and eating than in any other activity.

As we know, fish live entirely in water, so their food is limited exclusively to natural food sources found in the freshwater lakes and stream or the saltwater oceans where many varieties of seaweed grow.

So, to answer your question and not waste any time.

Do Fish Eat Seaweed? Yes, Herbivorous fish eat seaweed, but Omnivorous fish eat seaweed and animals. 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. Seaweed in home aquariums is usually kept to saltwater marine fish.

Herbivorous fish obtain their nutrients from vegetables, some feed on aquatic plants and other fish eat algae; this will depend on the depth at which they live. 

These herbivorous species need to feed constantly since they cannot properly assimilate nutrients.

This occurs because when eating plant-based foods, their digestion is slower and more complicated compared to fish that eat other animals, which is why evolution has provided them with longer digestive systems.

Watch These Saltwater Fish Enjoying Seaweed

Which Fish Eat Seaweed?

Like I mentioned before, many fish eat seaweed, especially herbivorous species. There are hundreds if not thousands of species of saltwater fish that eat seaweed

Here is an example of fish that you would not instantly recognise as seaweed or algae eaters but in fact they love it!

How to Feed Seaweed to Fish

I recommend using a seaweed feeder; this way, you won’t have seaweed floating around in the aquarium; this will help with the aesthetics and prevents the filters from blocking, and let’s be honest, it looks cool. Your fish will love it. 

It can be used by freshwater and saltwater fish, but mainly saltwater aquarium fish like Tangs, Angelfish and Wrasse.

It can be attached to the aquarium glass with a magnet.

Do Fish Eat Seaweed? | Freshwater and Saltwater 1

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Is Dried Seaweed Good for Fish?

Yes, and I recommend you use Nori.

Nori is a natural seaweed that is roasted or dried, and believe it or not, it is actually used as human food in oriental kitchens. I bet you love sushi. 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.

Usually, there are two types of Nori to choose from: red, which some of the time looks dark, green, and purple.

It usually comes packaged in full-size sheets, but you can cut it into pieces and pre-packaged it at some aquarium stores or suppliers.

For detailed information on Seaweed, this article from Feedipedia fits the bill.

Do Fish Eat Seaweed? | Freshwater and Saltwater 2

Seaweed sheets are perfect for Aquarium fish

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Seaweed FAQ

Do Shrimp eat seaweed?

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

Shrimps are very helpful for the maintenance of any aquarium; I call them the guardians; what they do is eat all the filamentous algae that are born inside these aquariums, keeping it 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 that occurs naturally on all continents of the world.

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.

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.

But basically, the herbivorous turtles consume seaweed and marine phanerogamic plants like Zoostera or Posidonia.

Do Snails eat seaweed?

Aquarium snails feed on plankton, a microscopic organism present in water. They can eat seaweed, but it is not so common. And you can offer them fish flake food.

How to Grow Seaweed

The best way to plant your Algae or any other plant is to get the right seeds and plant them in a good place.

Ideally, for the germination phase, the most recommended is to use a pot with fertile soil. However, if you can take advantage of any other aquarium tank you may have at home, it would be ideal, if not, something similar.

This is what you have to do:

1. Collect the seaweed seeds and soak them for several hours, to hydrate them.

2. Once this is done, it is time to put the Algae seed in the sand/soil, make a hole in the sand about 3-4 centimeters deep, and thick enough to fit the seeds.

3. Finally, it is time to cover the Algae seeds with a little soil and water.

Now it’s time to wait for the plant to germinate, which should happen after a few days if everything goes well.

I recommend using a fertilizer and aquarium heater; this will help to keep the water and plants in optimal temperature.

Do Fish Eat Seaweed
DoSeaweed is a natural source of vitamins for many fish and shrimps

How Important is Seaweed to Fish?

Basically, it is the food of many fish; it’s also a place where the smallest fish can take refuge.

Many fish eat their babies because they can be mistaken for food, especially when they are just born, so seaweed is safe haven for this small fish/fry.

Plus, it has many nutrients, which helps in the development of the fish.

Conclusion: Do Fish Eat Seaweed?

All fish in one way or another eat seaweed. It’s part of their life.

Seaweed provides proteins of high biological value and constitutes a valuable source of amino acids, vitamins, and minerals, including calcium, potassium, magnesium, zinc, iron, and iodine.

Seaweed is essential in an aquarium; they help simulate the natural habitat of fish.

So, if you don’t have seaweed in your aquarium, this is the time to start using them. 

Your fish will love it.

Carl Broadbent