6 Reef Safe Starfish for Your Aquarium

If you’re looking for interesting invertebrates to add to your aquarium, starfish may have caught your eye. They’re such a typical underwater inhabitant, but at the same time so alien and unusual that it’s easy to understand why they fascinate aquarists around the world. But beware: the majority of starfish are either not reef-safe or not suitable for aquarium life at all.

We could tell you about all the amazingly colorful starfish to be found in your local aquarium store, but what’s the use if your sea star would just starve within a few months, or worse, eat your reef?

That’s why we’ve compiled this list of 6 reef safe starfish, all of which actually have a chance of survival!

6 Reef Safe Starfish for Your Marine Aquarium

Beginner-Proof: Brittle starfish (Ophiuroidea)

Okay, we’re starting off here by cheating a little bit, because brittle starfish are actually not true sea stars. Still, with five arms and a central body, we’d say they’re pretty close. These echinoderms are members of the class Ophiuroidea and are characterized by their long, spindly arms.

Brittle sea star appearance is a little icky to some, but they really do make a good addition to some types of aquariums. They’re great for your cleaning crew and particularly good at disposing of detritus and leftover fish food.

Despite their name, these stars aren’t nearly as brittle as some other starfish: they adapt pretty well to life in a fish tank. They’re reasonably easy to keep and they won’t bother your livestock and corals as some other starfish species do. You’ll see yours coming out mostly at night to scavenge, although you can also try target feeding small pieces of fish if you can locate your starfish.

There are quite a bunch of brittle starfish species, some of which get quite large. If you don’t want yours to outgrow your aquarium, you could see if you can acquire some micro brittle stars. These don’t tend to grow larger than 2”.

Did you know? Brittle stars in general play nice with their neighbors, but you should avoid the green brittle starfish (Ophiarachna incrassata). This voracious predator grows large and can snatch fish!

Beginner-Proof: Serpent starfish (Ophiuroidea)

Serpent starfish are very similar to the aforementioned brittle stars. Both are members of the Ophiuroidea and don’t differ too much in terms of looks. Some sources consider the two names synonyms, but in the aquarium hobby at least, they’re seen as different. “Serpent starfish” tends to refer to Ophiuroidea with smooth legs, while “brittle starfish” have protrusions and tiny spikes on their appendages.

Although there are many species of serpent starfish, one we particularly like for the aquarium is the red serpent starfish (Ophioderma squamosissimus). These guys can get pretty big, but most aquarists we’ve spoken to report that theirs leave their livestock and reef alone, especially when well-fed. 

Their funky looks, bright color and detritus eating talents definitely makes this one worth considering if you’d like to keep a starfish. They’re also not as difficult to keep alive as some other species, although they do need careful acclimation to the aquarium.

By the way: if you don’t like the red variety, there’s also the banded serpent starfish (Ophiolepis superba), which tends to do equally well in the aquarium.

Did you know? Although starfish are often accused of snatching fish, it’s also important to consider the reverse. Those long legs can seem irresistible to some fish species, so it’s a good idea to avoid overly voracious specimens like pufferfish. 

Red Fromia starfish (Fromia milleporella)

Aside from the Ophiudoidea, one of the main groups of reef safe starfish commonly kept in aquariums are from the genus Fromia. The red starfish, or Fromia milleporella, is one of the species you might come across in your local aquarium store.

This sea star, which is also known as the black spotted starfish, is pretty neat to look at. It sports bright reddish-orange coloration, and its appearance isn’t nearly as off-putting as that of brittle and serpent stars! This being said, as great as all that is, any seasoned marine aquarist will know there’s always a catch

In this case, it’s the fact that Fromia milleporella is only suitable for large and mature aquariums. This is because its diet appears to consist of algae, biofilm, and sponges. It’s difficult to get these stars to accept supplemental feedings, if you can even figure out what exactly to offer them. As such, you’ll have to somehow manage to breed their favorite foods yourself.

The species is also sensitive to changes in water parameters, meaning you’ll have to acclimate it very carefully and take it slow while doing water changes.

For more information, you can have a look at our full red Fromia care guide.

Did you know? As you may have realized by now, the science is a little behind when it comes to many starfish species. We aren’t always entirely sure what they eat, and even their naming and classification can be incorrect! 

Orange sea star (Echinaster sp.)

This genus of starfish is reported to be pretty well-suited to aquarium life, with many aquarists saying theirs is still going strong a good while after purchasing it. Echinasters are also reef safe: Like Fromias, they feed mostly on biofilm, algae and sponges.

Our personal favorite would have to be Echinaster sentus, better known as the spiny starfish. You can recognize this one by its brown to blackish base color, dotted all over with small orange spines.

As long as your aquarium is reasonably large (50+ gallons) and mature, with plenty of live rock present for biofilm to grow on, you should be able to keep an Echinaster. You can supplement its diet using normal fish foods, which they generally accept. This being said, it can be a bit of a challenge to get the food to the starfish without its tankmates snatching it up.

Did you know? As you can see, the Echinaster starfish in the image above is missing part of one of its legs. Fascinatingly, starfish are usually able to regenerate lost appendages! In fact, a brand new sea star actually sprouts from a lost leg sometimes. 

Indian sea star (Fromia indica)

Let’s close out the list with another Fromia: the Indian sea star or F. indica. Although similar to the black spotted starfish, the difference here is in the black-tipped appendages, as well as the pattern, which is almost reminiscent of scales or mesh. The maximum diameter for this one is about 4”. 

Like other Fromias, this one is reef safe. It’s not herbivorous, as it does eat small invertebrates if it gets the chance. However, the species tends to get by mostly on general detritus and biofilm/microalgae.

If you want to keep an Indian sea star, you’ll need a large and mature aquarium. We’d say the minimum is 50 gallons, but 100+ would technically be preferable. To prevent shock, the starfish must be acclimated very slowly, and you should always avoid water parameter swings.

Definitely stay away from any copper-based medications, which are deadly to a variety of (invertebrate) aquarium inhabitants.

Biscuit sea star (Tosia australis, Anchitosia queenslandensis)

Warning: only reef-safe if well-fed!

As their scientific names suggest, biscuit starfish are mostly naturally found around Australia. Here, they inhabit shallow and relatively cool waters like rock pools, feeding on sessile invertebrates like sponges and bryozoans.

Biscuit stars really are very nice to look at; the ones sold for the aquarium trade are usually orange in color, but they can actually be many shades of brownish-purple, black, white, and grey. Their scale-like patterns, small size (max. 2″), and stubby, rounded arms make them easy to recognize.

Experienced aquarists can keep biscuit starfish in a mature aquarium of at least around 100 gallons. You should breed a steady supply of sponges in your sump or a separate tank. Note that no one is quite sure which sponge species they eat yet, but you can give the easy pineapple sponges (Sycon sp.) a try to start with.

For more information, have a look at our full biscuit starfish care guide.

Tip: Don’t confuse Tosia and Anchitosia stars with the more predatory Goniaster tessellatus, which is often called the West African biscuit starfish. Although G. tessellatus is easier to feed, using pieces of shrimp and the like, it’s also more prone to eating corals.

A note on Asterina starfish

It’s not uncommon to end up with a whole bunch of starfish in your aquarium without ever setting out to buy them! The genus Asterina is a common aquarium hitchhiker and hardier than any of the other species on this list.

The reason we didn’t include this species on the list is because of the fact that, despite some being great detritus feeders, they can reproduce so quickly that they’re usually seen as more of a nuisance than a welcome addition.

The Asterina starfish found in the aquarium are small, typically under an inch in length. However, they can be problematic. These stars eat anything (seriously, they even eat each other) and aren’t afraid of munching on your corals if other foods are in short supply. That’s why some aquarists actually use harlequin shrimp to get rid of what they consider infestations. 

Starfish we don’t recommend

As mentioned in the introduction, there are quite a few starfish for sale in the aquarium hobby that you might want to steer clear of. We wouldn’t write most of them off entirely, but unless you know exactly what you’re doing, buying one tends to be a recipe for disappointment.

• Linckia starfish (red and blue): From what we’ve seen, it can be done. However, you’d need to provide a very large and mature aquarium, because Linckias eat microfilm and the vast majority starves to death. 

• Sand-sifting starfish (Astropecten polycanthus): These are effective but overly enthusiastic cleaners that can decimate the life in your substrate and then tend to die from starvation. Again, it can be done, but be sure to think twice before buying one.

• Genus Protoreaster (red-knobbed starfish, chocolate chip starfish): Fine if you don’t have a reef, but these are voracious carnivores. A pity, because they’re by far the nicest species on the list to look at.

• Green serpent starfish (Ophiarachna incrassata): They get much larger than their red cousins and are also a lot hungrier. Even fish are said to be at risk.

Conclusion

Looking to add a sea star to your reef? The 6 species discussed here are reef safe and have a fighting chance (as opposed to some others, which are almost guaranteed to die).

If you’re a beginner, start with the top two options on the list. Our top recommendation would be a few mini brittle stars, such as Ophiocoma pumila. These are pretty hardy and make a great addition to your clean-up crew without growing overly large.

If you’re dreaming of a beautiful reef aquarium for your home and office, give us a shout. The FantaSEA Aquariums team is here to design, set up and maintain every type of fish tank you can think of!