Starfish or Sea Stars are one of the more unique and intriguing specimens found in reef aquaria. Whether you are a seasoned hobbyist or beginner, you are most likely familiar with these stars of the sea. They are available in a variety of brilliant colors and can perform a critical function in your reef aquarium.

This article will provide you with a bit more knowledge about Sea Stars and introduce you to the most common species available now in the aquarium hobby.

Sea Stars belong to the phylum Echinodermata, which also includes Sea Urchins and Sea Cucumbers. Sea Stars typically have 5 arms extending from a central disc in a radial symmetrical fashion. There are some exceptions to this, such as the notorious Crown of Thorns Sea Star and Feather Starfish. Sea Stars have the amazing ability to regenerate arms if one is lost. The bottom of each arm is covered in tiny feet that help the animal move and catch prey. These tiny feet are part of the complicated, hydro-vascular organ system which is one of the defining traits for Echinoderms. They also have a single mouth located under the central disc.

Sea Stars can be a great addition to established reef aquariums where naturally occurring food sources are readily available. Most Starfish are omnivores and will scavenge for food such as algae, detritus, copepods, worms, small snails and sponges. They are best kept in well-established systems. Be sure your Starfish will not have to compete with other animals for these natural food sources if you are considering adding one to your tank. Many hobbyists have success supplementing with fresh frozen foods and seaweed depending on the particular species of Sea Star being kept. A big oversight with Sea Stars is that they often die in captivity from what appears to be malnutrition or lack of suitable food sources. While Sea Stars can be effective in reducing detritus and cleaning algae, they can also knock over unsuspecting corals. Be sure to securely glue your frags and/or coral colonies before introducing Star Stars of any kind.

When choosing a Sea Star for your reef aquarium, be sure to do your research first. Not all Sea Stars are safe for reef aquariums because some of the species will prey upon coral. The most common of these predatory Sea Stars are the Chocolate Chip/Horned (Protoreaster nodosus) and Red Knobby Sea Star (Protoreaster linckii). Furthermore, different species have different feeding and habitat requirements so you will want to be sure your tank is suitable.

Upon bringing your new 5-legged friend home you will want to proceed with extreme caution. Most Starfish are very sensitive to air and should not be removed from the water. Furthermore, they need to be drip acclimated for a minimum of 60 minutes because they are very sensitive to changes in water chemistry including (but not limited to) pH, salinity, temperature and even oxygen levels. To learn how to use the drip method to acclimate a Starfish, please click here.

We gathered some useful information on the most commonly available "reef safe" Sea Stars below. This list does not cover every single Sea Star but will certainly help you to understand more about the different species and requirements for captive success.

Linckia Sea Star

Blue (Linckia laevigata) and Multicolored (Linckia multifora) are the two species readily available. They are excellent choices for reef aquariums because they have been observed feeding on marine algae and will readily accept prepared meaty foods such as squid, mysis and silversides. They are beneficial scavengers and are also very agile, able to navigate around coral frags and colonies.

The Multicolored species is much smaller and only grows to about 4", but has great success in aquariums. The Blue Linckia will grow much larger to about 16"maximum. Linckia Sea Stars reproduce asexually and simply drop one of the arms, which will then grow into another Starfish.

Sand Sifting Sea Star

(Astropecten polycanthus) These Starfish play a special role as they live inside your sand bed. They move cross the top and burrow into the sand feeding upon small animals such as crustaceans, worms, snails and possibly detritus. A sand bed depth of at least 4" with plenty of biodiversity will be required to keep one. They will typically starve if not provided with a large self-sustaining sand bed. A refugium area will help provide the biodiversity necessary to keep a steady supply of food.

With a hefty appetite and maximum size of 12", the Sand Sifting Sea Star is best kept only one per 100 gallons or more. They are beneficial to your system as they keep the sand bed churned and free of detritus build up.

Brittle Stars

These come in a variety of species—too many to list in this short article. This classification includes the popular Serpent Stars which all belong to the class Ophiuroidea. They are easy to spot as they have a large central disc with very thin arms usually lined with small spines. The most common species observed in reef aquariums are the black and white striped hitchhikers on your live rock which tend to stay small, maxing out at about 6".

Other species, like the "Green Death Star" (Ophiarachna incrassate) may grow up to 20" across. This species gets its nickname from being a semi-aggressive predator that will feed on small, unsuspecting reef fish as well as scavenge the tank for small prey. Some other common names for different species available are the Tiger Striped Serpent Star, Spiny Brittle Star and Red Elegant Brittle Star.

Brittle Stars tend to hide inside your rock work and extend their skinny arms to suspension feed on plankton and small prey. The majority of activity is observed at nighttime, although they will feed when food is available. They are great scavengers in reef aquaria and some species are quite prolific. They will feed on detritus, zoo plankton, and prepared bits of meaty food. Most species have great success rates in captivity.

Marble Sea Star

(Fromia sp.) This genus is very striking with a marbled appearance and interesting texture. A few different species exist within the genus with different color variations and texture. Red Marble Star and Elegant Star are other common names you may hear within hobby circles.

The Marble Sea Star is small with a maximum diameter of about 6". They are observed scavenging for small organisms and feeding on sponges. They may accept prepared sponge diets but are best kept in a large aquarium with well established biodiversity and natural food sources. Captive success is limited with starvation being a leading cause of failure.

If you would like to keep a Sea Star in your saltwater aquarium but aren't sure if your tank is Starfish-ready, feel free to contact us for free advice. If you already have a Starfish in your tank, please share your experiences with us and other readers below in a comment. Thanks for reading!