What do Starfish Eat?

What do Starfish Eat?

Starfish are beautiful and unusual creatures, even though they are found all over the world. Starfish are slow-moving and have a striking presence in an aquarium, so many people want to keep starfish as pets. If you are considering adding starfish to an existing aquarium or cultivating starfish as pets, you may be wondering what do starfish eat. Let’s learn more about the eating habits of these incredible sea animals.

How do Starfish Eat?

Starfish have a mouth located in the bottom center of their bodies, surrounded by their arms. Most starfish species use their legs or feet to direct food toward the mouth.

Many starfish eat by wrapping their legs around marine animals, allowing digestive fluids from their mouths to slowly weaken tough exterior tissues.

Starfish often prey on shellfish by using their strong arms to slowly pry open the shell and eating the shellfish within.

Some starfish species can evert their stomachs, sliding their stomachs into a narrow opening in the shell and using their stomach to surround and partially digest prey before absorbing it fully into their bodies. This allows them to eat animals much larger than themselves.

Some starfish species can also absorb organic nutrients from the surrounding water to sustain themselves passively, with less active hunting and eating. Some starfish are suspension feeders, harvesting algae directly from the water.

Because there are so many starfish species, each may eat a different diet in a different way. When considering keeping a starfish, it’s essential to research the specific species’ needs and habits to ensure that you have a suitable environment for them.

What do Starfish Eat in the Wild?

In the wild, starfish are keystone predators, often crucial to the healthy balance of the ecosystem in which they live. Starfish have been known to eat nearly everything in a marine environment, including:

Algae and Microalgae

Some starfish species eat microalgae suspended in the water, while other species are famous for eating algae film.

Sponges and Tubeworms

Starfish will happily eat soft tissues belonging to sponges, tubeworms, and similar sea life. However, some starfish species will easily coexist with sponges, enjoying the beneficial water current sponges create.

Bivalves and Snails

Starfish are most known for eating bivalves, snails, and marine shellfish. Their arms have suction discs that allow them to slowly pry open the shell, exhausting the adductor muscles of the animal within.

Some species can evert their stomachs into a shell, needing only a tiny opening to consume shellfish. Other species of starfish simply overpower a bivalve and open the shell.

Coral Polyps and Sea Urchins

Some starfish species can eat their body weight in coral every night, extruding their stomachs to digest coral polyps. They eat sea urchins and other tougher marine animals the same way.

Decomposing Organic Matter

Many starfish species simply graze on various decomposing organic plant and animal material in the ocean, helping clean the marine environment.

As you can see, starfish will eat nearly anything they can get hold of with their powerful arms and feet, and most species are specialized for their unique environment.

Types of Pet Starfish

Starfish are strictly saltwater animals and require a large living environment to thrive. Most species need at least 100-gallon aquariums to satisfy their healthy water requirements and active foraging for food. Some of the most popular aquarium starfish types are:


Sand Sifter Starfish are peaceful and reef-safe. They can live in a tank as small as 10 gallons and grow slowly, reaching up to 12 inches in size. They require a fine sand substrate and cannot get over rocks, and do best in an established tank with rich food sources.


Linckia are known for their vivid colors and beauty, and they can reach up to 14 inches in size. Linckias require huge tanks with a sandy bottom and live rock, where they live on biofilm and little else.

Linckias are extremely sensitive to water conditions and prone to some diseases and parasites and are best cared for by experts.

Brittle and Serpent Stars

Brittle and Serpent starfish are peaceful and reef-safe. They live for several years in good conditions and reach 12 inches or more in size. They feed primarily on detritus and require a 20-gallon tank or more.


Fromia is another brightly colored, reef-safe starfish. They reach about 6 inches across but seldom survive longer than a year in a home aquarium.

While they are omnivores and will eat a wide range of foods, they require a very well-established tank, 60 gallons or more, with a thriving community of micro-organisms. Unfortunately, many fromia starve despite being offered a wide range of foods.

Chocolate Chip Starfish

Chocolate chip starfish have a striking appearance. They are not reef-safe, as they will eat corals and small invertebrates. They live for 5-7 years and reach 6 inches or more in size. Also, they require a tank that is 30 gallons or more and require regular feeding.

What do Starfish Eat

What do Pet Starfish Eat?

If you want to keep starfish in an aquarium at home, it’s essential to research your specific starfish species.

Because they are such diverse, opportunistic predators, they will often eat other animals in an aquarium environment and may destroy a delicately-balanced aquatic system. When keeping starfish at home, they will eat:

Fish Food

Most starfish are grazers that will eat fish flakes, pellets, and other food that falls to the tank’s bottom.


Many starfish will also eat algae film and help to clean a home aquarium.


Most starfish species naturally eat a diet high in bivalves, so feeding clams or mollusks will help keep them healthy and happy

Sea Life

Many starfish happily eat typical aquarium food like shrimp, sponges, and prawns.


Some species of starfish will also snack on leafy greens like spinach and kale

A pet starfish needs a healthy diet and a healthy environment to thrive in an aquarium. Most starfish are active foragers who need a live rock and established reef environments to stay healthy.

Remember that starfish may be misidentified by sellers, so do independent research to verify which starfish species you are considering and what diet and environment that starfish require.

Will Starfish Eat Other Marine Life in an Aquarium?

Yes, starfish will often eat other fish and organisms in an aquarium. Here are some things to keep in mind when creating a marine ecosystem for your starfish.


The Crown of Thorns starfish primarily eats coral polyps, and a Chocolate Chip Starfish enjoys coral as well, so they should not be kept in a coral environment.


Most starfish species, including Chocolate Chip, Pacific Blood, Leather Starfish, and Egyptian Sea Stars, will eat sponges.

Snails and Hermit Crabs

The shells of snails and hermit crabs won’t protect them from starfish like the Egyptian Sea Star or Sunflower Star.

Algae and Plankton

Many starfish will eat aquarium algae, including Egyptian Sea Stars and Pacific Blood Starfish.


Most starfish species will eat clams, mussels, and shrimp, including Chocolate Chip Starfish, Marble Sea Star, Sand-Sifting Starfish, Linckia Starfish, Leather Starfish, and Sunflower Star.

Fish and Fish Eggs

Leather Starfish will eat fish eggs, and most Brittle and Serpent Starfish will eat small fish if they are hungry.

How to Feed a Starfish

Starfish will forage over an aquarium environment, but most species should still specifically be fed. Most starfish require food every two to three days but adjust your schedule based on your individual starfish’s needs.

You can tell if a starfish is hungry by placing food near them, and they will quickly move over the food and eat it. If you are concerned about other aquarium inhabitants eating the food first, you can place a starfish on top of their food so they don’t have to compete for it.


Starfish are best in large, well-established tanks with thriving ecosystems and often require expert care to live and thrive.

Because there is still so much we don’t understand about these animals and they are so incredibly diverse, it’s essential to thoroughly research starfish species before choosing to add one to your tank.

However, if you decide to have a starfish at home, they can make an exciting, beautiful, and dynamic addition to your aquarium.