The Chocolate Chip Starfish are quirky sea water fish.

They are star-shaped. Small dark cones, knobs, or spines (tiny conical horns) cover their entire upper (dorsal) bodies as if they are garnished with chocolate chips, naturally.

They resemble star-shaped chocolate chip cookies, explaining their name.

The Starfish are not Fish since they do not have fins or gills and are invertebrates (with no backbones). Hence they are called Sea Stars.

They are easy to care for, affordable, and sturdy, making them appealing for both – beginners and experts.

If you are new to them or thinking of adding something “out of the box” to your marine aquarium, Chocolate Chip Starfish is a good choice.

This article covers everything you need to know about caring for them or deciding if you should own one.

Did you know? Chocolate Chip Starfish are an endangered species in Singapore. Their decreasing population all over the globe is a growing concern.

Generic Facts

Table 1 – Generic Facts
Scientific Name ProtoreasterNodosus
Other Popular Names Horned Sea Star, Horned Starfish, Knobbly Sea Star. Nodular Sea Star
Family Oreasteridae
Origin Indo-Pacific Region
Life Span Up to 20 years in the wild, 7+ years in Captivity
Adult Sea Star Size 12 to 15 inches
Type Marine or Saltwater fish

Habitat and Origin

Originating from the Indo-Pacific region, they live in the Red Sea, Indian Ocean, and Pacific Ocean.

Areas surrounding the Philippines have a high concentration of their population.

These shallow lagoons, seagrass meadows, and sandy ground-dwellers are also known to venture 75 feet deep in the Indo-Pacific reef regions!

They cannot survive in freshwaters or breathe outside seawater even momentarily.

Physical Attributes and Size

As informed earlier, the Chocolate Chip Sea Stars resemble star-shaped chocolate chip cookies.

The small conical knobs are sharp and shiny. But as time passes, they become rounded and dull in color.

Nature has adorned them with colors that help them camouflage in their habitats (like brown, red, ivory, blue, reddish-brown, yellow, or vibrant combination colors) in different regions.

Their average lifespan in aquariums is 5 to 7 years, but they may live up to 10 years or more with better care.

Anatomy of the Chocolate Chip Sea Stars

Did you know? – Sea Stars have no brain or blood! They have a water vascular system that circulates seawater into their bodies to get essential nutrients.

The below images explain their anatomy.

The first image describes the upper body:

  • Five arms (arms are also called rays)
  • Trivium – top three rays (1, 2, and 5)
  • Bivium – the lower arms (3 and 4)
  • Madreporite – Or the “sieve plate, is a calcium-based opening between the bivium

The sea stars open it to bring filtered seawater into their nervous system and close it to prevent air bubbles from entering it

The second image shows the detailed upper body:

  • They have an eye at the end of each arm (points 1, 16, 17, 32, and 33). Thus, five eyes
  • Point 41 – the central disk is vital for their survival

It also acts like their mouths.

The third image details all the 41 points shown in the previous image: 

The fourth image shows their backside.

  • It has a continuous linear series of tube feet with tiny suckers at the end, connecting the central disk to the end of each arm.

The tube feet are multi-purpose. They help to:

  • Crawl, hold, or break the food
  • Stick on the aquarium glass or any surface
  • Exchange gases (to breathe)
  • The skin on the backside is light-colored, generally pink or purple
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Male Vs. Female

We cannot differentiate the gender of Chocolate Chip Sea Stars until they breed. Even then, a microscope is needed to check their gender.


The price of a Chocolate Chip Sea Star ranges from $12 to $40, depending on the size, availability, and offers.

We recommend you always purchase from reliable sources (online/offline). Follow their care instructions to the tee to avail of after-sale support.

How to Select

Do not buy from the “newly arrived” stock in the shop. You never know how healthy and well acclimatized it is.

Select medium-sized sea stars, provided they have been in the shop stock for a while.

You never know how a small one might exhibit newer issues later. An older one could be too large and costly.

If you purchase online, examine carefully upon receipt for any visible issues (scratches, spots, faded color, disfiguration, etc.). Improper shipping can cause stress to them.

Did you know? Due to some anomaly, there are rare occurrences of Chocolate Chip Sea Stars having 4 or 6 arms instead of five.

Care Guide

Table 2 – Chocolate Chip Sea Star Care Overview
Care Level Easy
Diet Omnivorous
Temperament Non-aggressive, Slow moving (crawling)
Breeding Difficult
Social Opportunistic Carnivores


The Chocolate Chip Sea Stars are opportunistic carnivores and scavengers.

They thrive on almost anything except their predators.

  • Decaying plants/animals
  • Algae, Debris
  • Any smaller, slow-moving, and non-moving (sleeping) fishes
  • Smaller sea stars

Feed them various foods (like squids, shrimps, meaty foods, bivalves, etc.)

They also eat anything floating in the tank water.

Thus, they clean your fish tank by eating the debris and suspended food, provided the tank decor is spacious for them to move freely through it.

When and How to Feed

A sea star requires feeding every two to four days.

It mostly sticks to the aquarium glass. Take the food near its arm with your hand (or use tongs) and wait.

If hungry, it will stretch its arm to grab it. If not, it will not respond at all.

Be patient, as they are slow. Be it crawling, stretching arms to grab the food, or eating it.

Feed them, either first or last, ensuring their morsel is not eaten by competing tank mates.

They are more active at night (remember – scavengers and opportunistic carnivores). So try feeding at night.

Typical Behavior Patterns

Did you know?– Chocolate Chip Sea Stars push out their stomachs from their mouths to eat and digest food. Once done, their stomachs push back inside their mouths!

Their typical behavior patterns are listed below:

  • As indicated above, they eat unusually. Watching them eat in your home tank is a priceless experience.

Once the stomach is out of its mouth, tentacles around the mouth hold and break the food. Digestive juices help digest it.

  • Their mouth opening also doubles up as an outlet for their body waste.
  • They use their senses of sight and touch to navigate.

Natural self-defense

Did you know? The Chocolate Chip Starfish can restore its lost arm(s) to normal by growing it again, as long as the central disk is intact.

  • Their natural colors help them camouflage in their habitat.
  • The upper body skin is thick and formed of calcined plates.
  • The conical knobs give it a scary appearance to keep predators off.
  • They prefer to remain hidden (under shallow muddy waters, sandy lagoons, seagrass leaves, or coral sand) to avoid predators.
  • They can regenerate lost arm(s).
  • If a predator has not clinched its arm but just got hold of it, the sea star can detach only that arm (on its own) and swim away to save itself.


The sea stars reproduce Sexually and Asexually.

Sexual reproduction is by spawning, where the male sea star releases sperms and the female sea star releases eggs into the water.

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The eggs fertilize outside their bodies in the water.

A sexual reproduction is where the sea star regenerates its lost arm(s) single-handedly,

Breeding in the Wild 

Understanding how they breed in the wild will help understand the challenges of captive breeding.

  • They gather in large numbers in the spawning season.
  • They spawn on full moon day, at a particular water temperature and salinity (hitherto unknown).
  • They breed only in deep waters (maybe to ensure fertilization).
  • Together, they release millions of eggs and sperm at the same time.
  • The eggs and sperms float in the ocean waters till they fertilize.
  • Thus, water currents largely influence their fertilization rates.
  • The fertilized eggs are 0.2 mm in size and are not visible to the naked eye.
  • They float in the waters, feeding on the plankton and algae in the first month.
  • During this phase, their bodies metamorphize forms (like larvae, blobs, etc.).
  • After one to two months, they form a tiny star-shaped body, followed by detailed anatomy in the coming months.
  • The baby sea stars feed on minuscule plants and animals in the sea.
  • They remain hidden (between plants, reefs, rocks, etc.) for the next few months to guard against predators.
  • They venture into the open waters only after they grow sufficiently large.
  • By the age of two to three years (about 2-3 inches in size), they are sexually mature.
  • Know more about Fish Breeding, Caring for Eggs, and Feeding Frys.

Challenges in Captive-breeding

It is difficult and rare to breed a Chocolate Chip Sea Star in aquariums since:

  • The depth of the home tank is not deep enough for them to spawn.
  • It is practically impossible to replicate the exact water salinity and temperature to spawn them on a full moon day.
  • Until they spawn, you never know if you have two different or same-gender sea stars.
  • Even if they spawn, you will not realize it, as the fertilized eggs and their metamorphosis is not easily visible to the naked eye for several months.
  • They might be eaten by their parents/other fishes in the tank before you know it.

Please refer to the Tank size section to know how many you can add to your aquarium.

Glimpses from a study

A study observed the following regarding their spawning:

  • One of the 22 specimens under observation arched on all its arms (this is the position female sea stars take when spawning) on the 4th of May.
  • A water sample examination did not reveal the presence of any eggs on that day.
  • On the 6th of May (a full moon day), six female sea stars released eggs between 11:00 am to 1:00 pm.
  • Subsequently, they observed numerous eggs and embryos in the tank bottom and on sea stars’ bodies.
  • Embryo samples collected from 1.5 to 3.5 hrs (from 1:00 pm on the 6th of May) showed them in various (2-64) cell stages.
  • The below image (8 A, B, C, and D) depicts stages of embryo growth with observations copied below
  • After 24 hours, the embryos fertilized (50% of them were in the growth stages 8 A and B).
  • On the 4th to 5th day of fertilization, the larvae developed mouth, esophagus, and stomachs (refer to image 8C).
  • Two arm forks were visible (refer to image 8D) on the 7th day from fertilization.
  • There was no further development till the 13th day.
  • The embryo cultures crashed due to unknown reasons on day 13 from the fertilization.
  • The further study of the embryo growth stages remained incomplete.

Did you know?  Tiny Filefish, Shrimps, and Brittle Stars take shelter on the Sea Stars for safety.


Chocolate Chip Sea Stars are strong and have natural healing abilities par excellence.

However, they are sensitive to any water changes because:

  • Water to them is what blood is to human beings.
  • Any water changes can cause them undue stress and lead to further complications.
  • They can sustain gradual water changes only.
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The most common diseases they are prone to are

  • Marine Ich/Ick
  • Velvet

We recommend that you consult a vet for timely detection and treatment.

Table 3 – Other Issues
Name Description Precautions
Toxicity To Copper-based and Anti-Parasitic medicines

Don’t use any of these to treat them

Isolate them if other tank mates need any of these


Twisted arm tips or weirdly stretched arm(s) as it  tries to reach algae coating in the water

Curls up into a ball

If observed more frequently, fix and maintain the tank water parameters

Consult a vet

Sensitivity and Stress factors to be avoided
  • Handling/touching. Wear gloves if you must handle them.
  • Ammonia, Nitrates, and Nitrites poisoning due to poor tank water quality.
  • Smell of human body products (perfumes, sunscreens, etc.).
  • Overcrowded tank.

Most complications begin from tank water quality or malnutrition (leading to low immunity). Maintain these, and your sea star will thank you.

Visit to know about the root causes of diseases, and their prevention and treatment.

Acclimating Chocolate Chip Sea Star

Sudden water changes can kill a sea star.

Hence, you need to acclimate it to the tank water so that its body adjusts to the water change gradually.

You need to acclimate your sea star for 2 to 2.5 hours.

Post-Acclimating, your new sea star is ready to meet its tank mates.

Place it quickly and gently on a rock in the tank without exposing it to air. Patiently wait for it to enter the tank water on its own.

Click here for more information about different acclimation processes.

Tank Recommendations

Table 4 – Tank Requirements Overview
Minimum Tank Size 20-30 Gallons (approx. 80 to 100 liters)
Water Temperature 72 to 80 degrees F (22 to 27 degrees C)
PH Level 8.1 – 8.4
Water Hardness 8 to 12 dKH
Nitrate level Less than 20 ppm
Water Salinity 1.021 – 1.025 SG (Specific Gravity)
Reef Tank Compatible No (They will eat Sponges, Corals, etc. decor)

Tank Size

It is advisable to add a single Sea Star to your marine aquarium, considering it can grow up to 15 inches and live for 7-10 years.

Besides, it can exist peacefully with other tank mates (refer to the Tank Mates section), and most people prefer a variety in their fish collection.

If you wish to add more than one, maintain the ratio of 6 gallons of water per inch. It gives a fair estimate.

  • Decrease your tank size by the percentage occupied by the substrate (say 10%).
  • Divide the balance free capacity by 6.
  • The answer represents the maximum size of a sea star you can keep in the tank.
  • Ensure that all the sea stars are of the same size at all times.
  • Else it will be heartbreaking to lose the smaller sea star as prey to the larger one anytime.

Tank Setup

A FOWLR (Fishes Only With Living Rock) setup is recommended.

Try and replicate its natural habitat to keep the sea star healthy and happy. Ensure everything you add is bacteria/parasite/copper-free.

Substrate and Décor

A thick layer of sand (as in beaches, lagoons, and coral sea beds) coupled with live rock decor is best.

You can buy them from reliable sources.

In their natural form, these come with inbuilt good micro bacterial growth, algae, etc., which act as natural biological filters for the aquarium.

You can add other decors like bridges, stone structures, etc., as per your taste. Ensure there are no sharp edges, and keep enough space between them for the sea star to move freely.

Visit to find the ideal Tank for your Starfish.


Chocolate Chip Sea Star requires a high Intensity or full spectrum lighting.


Don’t add any live plants as the sea star might eat up your costly decor.

Oxygen and Filtration

They need a powerful filtration system.

Use biological and mechanical filters to maintain tank water parameters.

Avoid chemical filtration consisting of copper or anti-parasitic medication.

Click here for more about the different types of tank filtrations.

Tank Mates

Tank mate fishes: Dwarf Angelfish, Clownfish, Tangs, Damselfish, and butterfly fish.

Tank mate shrimps: Red fire, Peppermint, Skunk, and Camel.

Avoid predators: Boxerfish, Pufferfish, Triggerfish, Harlequin Shrimp, etc.

Don’t add possible prey: Slow-moving shrimps, smaller sea stars, anemones, Clams, Shellfish, Corals, Sea Urchins, etc.

Frequently Asked Questions

Most of your queries must be resolved now, except the ones listed below.

1. Are the Chocolate Chip starfish poisonous?

No, they aren’t.

2. How do I know if my Chocolate Chip Starfish is dying or dead?

Please refer to the Diseases section above for more details.

A dead sea star will look shrunk and droopy as if all water from inside is flushed out.

If dead, it will not respond to stimuli (like a gentle touch on its tube feet).

As a final check, try lifting them gently without removing them from the tank.


We hope you are empowered to deal with your favorite sea star or clear about owning one.

These star-shaped chocolate chip cookies will invariably steal the limelight of any aquarium with their ornamental looks, unique ways, and abilities.

About the Author

Shelby Crosby

Shelby is a passionate fishkeeper who has been writing about fish for over 5 years. She is a pro aquarist and holds a BSc Honors Degree in Wildlife and Fisheries. She creates her own beautiful aquarium layouts and loves to share her knowledge of tropical fish with other hobbyists.

Career Highlights:

  • Has worked with several aquarium manufacturers as a consultant
  • Organized and hosted workshops on freshwater fish keeping at retail stores, educational facilities, and libraries
  • Released content for the amphibian community through her writings

Educational Highlights:

  • BSc Honors in Wildlife and Fisheries in 2011 (University of Northern British Columbia)
  • Completed her undergraduate thesis on the effects of zoochlorella supplementation on the growth and health of fish.

Writing Experience

Miss Crosby is a Freelance blogger; many of her articles are posted online on various blogs. She has also written a few short articles for "Tropical Fish Hobbyist Magazine" in the past. She is a regular contributor to Her education, first-hand experience with fishkeeping, and in-depth knowledge in aquaculture make her one of the most competent writers in the industry.

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