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With progress in natural marine aquarium keeping, increasing
numbers of so-called "starfish" successfully
reproduce. Applications like deep sand beds and refugium
habitats seem to support such success. Some species
may become a nuisance by their sheer numbers and prolific
nature like Asterina, while others are clearly
harmless or helpful by stirring detritus or consuming
algae, for example.
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This article covers a range of sea stars
kept in aquaria, including the deliberate and incidental imports,
the decorative and nuisance, or predatory, ones alike. The
proper care of sea stars has long been an area of the hobby
in need of improvement. It pains me to see fellow aquarists
innocently add these animals to variously themed tanks with
hardly a thought for what these creatures eat or need to survive.
Many folks assume that "starfish" are simply deposit
feeders that will somehow find what they need by grazing about
the tank. In fact, very few sea stars can live wholly on the
incidental matter that grows or collects in aquarium systems.
Moreover, very few aquariums are even capable of growing enough
food matter, by weight, to sustain even a single Asteroid
(more about classes and groups below). In traditional "garden
reef keeping," most of us strive to limit nutrients and
nuisance algae by underfeeding and the use of skimmers, other
grazers (such as Turbo snails, tangs, and urchins)
and the cultivation of dominating coralline algae species.
This tends to produce "lean" rocks and sand without
much soft matter for a sea star to graze upon. In aquariums
where suitable food matter does grow for surface-grazing sea
stars, insufficient surface area, and hence food, per starfish
is oftentimes a limiting factor. Undersized aquaria or overstocked
tanks will not produce an adequate supply of potential food
matter. The sobering reality about sea stars is that many
slowly starve to death within a couple of years, if not mere
months, of importation. Making the matter worse, a significant
number of collected stars do not survive the importation process
to reach a consumer's tank. To be clear, I do not mean to
criticize the keeping of sea stars at large. Rather, it is
my intent is to acquaint fellow aquarists with some potentially
surprising realities about the collection, handling and keeping
of these fascinating animals with hope for a more conscientious
and responsible use of this group.
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The beautiful Blue Linckia sea star is perhaps
the best known and most popular and sought after variety.
They have rather poor rates of survival with aquarists.
Most folks tend to do quite poorly with individuals
of this species, exacerbated by sensitivities in shipping
and handling. For best success, buy these creatures
only on sight and after at least five days of acclimation
(stabilization) to a dealer's tank. After that, it is
advisable to stock them in mature aquaria with aged
live rock and few other grazing fishes or deposit feeding
invertebrates. A good rule of thumb is a maximum of
one Linckia laevigata per 100 gallons.
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Ask yourself when making decisions, particularly
about unfamiliar or notorious livestock for your aquarium,
"Do I have an adequate understanding of its needs?"
Are you likely to succeed in keeping it for its potential
natural lifespan? Do you currently have the means (adequate
tank size, age and continuous food source) for keeping it,
and not merely the hope of improvement, such as a bigger tank,
one day? There are other ways to contemplate such purchases;
such as, "Is my purchase a conscientious use of this
animal?"
Now the definition of what is conscientious
use is, to some extent, subjective. But without hiding behind
the guise of an infinite amount of "what ifs" or
superlative claims and demands, we should be able to agree
on the fundamentals, much like the citizens in a commonwealth
collectively agree on laws that are "reasonable"
to the majority of a given constituency, which all obey for
the greater good. Let us simply begin then by addressing that
which we could agree is sustainable harvest, from the perspective
of empathetic aquarists that regard the life in our tanks
as something more than a mere commodity.
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At least several species of sea star (including common
Protoreaster species), from both tropical and
temperate waters, are imported under the common name
'Chocolate Chip Starfish.' They tend to be categorically
risky as predators in the long term for tanks with mixed
reef invertebrates. They often suffer severe rates of
mortality upon importation. It is their low price that
perhaps contributes most to the continued popularity
of, and tolerance for, these varieties, despite their
dubious behavior and suitability for casual keeping
in community tanks.
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To sum up my position from the start: I
believe that an excess of sea stars die between point of collection
and final destination of importation, and that too many sea
stars successfully imported die within a year of entry to
the trade. The reasons for the latter are exacerbated by aquarists
who keep these (really, any) creatures casually
without: 1) understanding their needs, 2) offering specialized
care and 3) adequately target feeding. All of these challenges
are sometimes easily overcome with responsible investigation
before making a purchase. Start by finding out
where exactly does the animal come from on the reef - hard
or soft substrates? Some starfishes' feeding preferences are
remarkably challenging, as with feather or basket stars filter-feeding
on plankton. They may require very specific plankters and
even specific types of water flow to have adequate feeding
opportunities. Other stars forage around sand, mud and silt
for their sustenance and may fare poorly on hard substrates
like typical reef aquariums. Other systems with healthy deep
sand beds and refugiums that support large worm populations
may find certain starfish prosper in concert. Hmmm… let
us also not forget the predatory feeding habits of Ophiarachna
incrassata, the infamous Green Brittle Star that sits
with a fishing pole and drinks beer while listening to country
music. Indeed, the feeding habits of "starfish"
at large vary widely and it is imperative that aquarists understand
their specific animal's needs in advance.
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Ophiarachna
incrassata, the infamous Green Brittle Star, and
a few related kin are the rare exceptions to the otherwise
reef-safe and well-behaved Ophiuroid serpent and brittle
starfish class. In some tanks O. incrassata will
behave for months or even years, while in other tanks
they tend to catch and kill motile creatures whenever
possible They are active predators, which arch their
central disk above their legs to form a trap for fishes
and other prey. A lurker pictured here.
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Considering the former concern asserted,
namely that many sea stars die before reaching consumers,
it would be easy to think that we hobbyists have no control
here. You do not know the collectors personally, or have a
voice in the practices of the airlines transporting the sea
life. You do not necessarily know your retailer's sources
or have access to a direct line to express your concerns to
them. All of this is true. But you do have the
ultimate power over all in the trade of any consumer good,
be it stereos or starfishes: your buying decision! Our aquarium
hobby and trade, like most any act of commerce, obeys currency.
If you stop buying it, they will stop selling it… whoever
'they' are. And so, the case I put forth to you is that with
so many other hardy and beautiful creatures available, why
use any species of dubious value or questionable sustainability?
For example, the sale of live "feeder
starfish" as prey for the beautiful Hymenocera
Harlequin shrimp is not uncommon. This shrimp has long been
believed, at least in popular literature, to feed only on
the tube-feet of certain sea stars. As an aside, they have
been observed, anecdotally but often, to actually feed on
other echinoderms and other parts of these various animals.
Within the genus Asterina are one or more species of
stars that are prolific in reef aquaria. They usually appear
accidentally and have been cultured by aquarists to feed Harlequin
shrimp as an alternative to wild-harvested sea stars. Merchants
and aquarists may not know of, or may choose to ignore, these
other options, though, and rationalize the sacrifice of wild-caught
specimens with a claim of light usage, of say - one large
wild-caught star per month. The popular imports, however,
suffer remarkably high morbidity and mortality just to funnel
one healthy live starfish down to the merchant. So we must
ask ourselves, how many specimens can be permissibly sacrificed
in transit to successfully fill one order: one, two, ten,
or more? None need be sacrificed, in my opinion, when Asterina
is an easy and available home-grown alternative. Even if such
options did not exist, we still would have to practice responsible
use of wild-caught species. Losing several dozen collected
stars annually to provide one live one per month as a "feeder"
is not conscientious from my perspective. In such matters,
let us not forget the hard lessons learned by our fellow aquarists
in Europe: if you do not adequately police yourself, someone
else will do it for you! And it should not take government
or legislation to get us to make sensible, if not empathetic,
buying decisions like this.
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Although sea stars like the aforementioned blue Linckia
and this Purple Leiaster (pictured here), have
shared reputations for their gross similar appearance,
the reality is that their survivability often differs
substantially. Because this purple species is far less
common in the trade, and therefore more valuable, they
tend to get handled better with larger bags and more
water in transit. Subsequently, they may enjoy higher
rates of successful establishment in captivity. Aquarists
should use such insight to strategically select species
that are better choices in the long run for both themselves
and the hobby.
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The following evaluations of sea star species
or varieties as "favorable/best of," or "unfavorable/worst
of," take into consideration a wide variety of issues.
Some potentially excellent aquarium species can make the "worst
of" list because of present shipping realities (strategically
poor sources of origin - unavoidably extended duration of
transit, poorly funded or prepared collection communities,
etc.). Putting aside my own reservations about "rules
of thumb" or gross generalizations, I offer the following
categorizations of the classes of sea stars, which I believe
are fair and accurate:
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Common and so-called "fancy" Ophiuroids like
this banded species are available from Florida. They
are hardy, ship well and live long once established
with modest but faithful husbandry. Feed small amounts
of mixed green and meaty foods several times weekly.
A fine scavenger for beginners and newer aquaria that
are regularly fed.
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Ophiuroids - Serpent Stars: with the exception
of basket stars (see overview of Crinoid feather stars below
as similarly challenging), the majority of serpent and brittle
stars are hardy and suitable for home aquarium life. Many
will fare well even in smaller aquariums (under 20 gallons),
provided that they are target fed at least weekly. Most are
harmless, if not helpful, in reef displays as innocuous bio-turbators
(sand-stirrers), eating particulate matter or at least keeping
it in motion or suspension for nutrient export processes such
as skimmers and mechanical filters. They are the least discriminating
and most adaptable feeders of all "starfish." Unlike
other popular clean-up creatures (hermit crabs, perhaps most
notoriously), Ophiuroids are only a light burden on the bio-load
and bio-diversity of the system. Numerous species in this
class are suitable for beginners. Species native to tropical
Florida waters are highly recommended for aquarists for their
utility and ease with which they can be successfully collected
and shipped to aquarists in the United States - short transit
time, frequent direct flights to distributors, and hardy by
nature once established.
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Even ornate Ophiuroids tend to be hardy and long-lived
once established in reef aquaria. They enjoy rocky habitats
and will usually accept a wide variety of foods.
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Crinoid - Feather Stars and Sea Lilies:
there is very little to discuss here regarding this extremely
challenging class of organisms. I won't even pay lip service
to the noble charge, "If an advanced aquarist works hard
enough and sets up a species-specific system just for [Crinoids],
there is a chance of success." Point blank: please do
not keep or encourage others to keep these creatures at this
time. Why? You may ask. It's a fair question, indeed. Sadly,
the overwhelming majority of specimens will perish within
weeks or months of collection. They are notoriously delicate
and weak shippers. Their dietary needs are poorly understood
and difficult, if even possible, to meet in aquarium systems
(i.e., steady supplies of enough of the right kind and quantity
of plankton, bacteria, etc.). The few specimens out of hundreds
that do survive six months or more in captivity simply do
not justify the collection of so many others, which die to
pave the way for the arrival of each live one. This is one
of those groups of reef creatures for whom we must step forward
and make a conscientious choice not to support the collection
of for casual keeping or impulse purchases. To any aquarist
that disagrees with this position, I respectfully ask him
to soberly consider the effect that the promotion of keeping
such species to the masses does, and to kindly document, if
possible, any unique successes of several years or more with
Crinoids, rather than simply reporting specimens that took
6, 12 or 18 months before finally starving to death.
Asteroid Sea Stars - classic body "Starfish":
without stepping down completely from the anti-Crinoid and
anti-Basket Star soapbox, I come to perhaps the most underestimated
class of sea stars, the Asteroids. While many aquarists will
agree that Ophiuroids are generally hardy and easy to keep,
and that Crinoids are difficult to keep, the classic Asteroid
"starfish" species are largely mishandled and often
suffer very badly for it. Species from this class often carry
the erroneous reputation of being good scavengers (like Linckia
species) that magically live off of whatever organic film
happens to be growing in the aquarium, assuming that beer
nuts and salty pretzels are not available to eat instead.
Unfortunately, some are so remarkably inexpensive to import
for sale that consumers can buy one weak and dying specimen
after another with little incentive (beyond ethics) to stop
and consider the suitability of the species or source for
aquarium use. Alas, this class includes many of the most beautiful
sea stars known to man. All is not doom and gloom, however,
for keeping Asteroids. Unlike filter-feeding crinoid and basket
stars, most of the difficult Asteroid species are not inherently
challenging to keep alive. Given an appropriately constructed
set of physical parameters in the aquarium, and a healthy
import, many Asteroids can be kept with relatively little
effort. They do, however, require specific care. Most are
carnivorous and target specific prey that may not exist or
be adequately produced in aquaria to sustain them (particularly
smaller aquaria). Most species in this group are not "reef
safe."
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A small but steady stream of larger, novelty Asteroid
sea stars seems to always trickle into our hobby. Some
of these pillow, pincushion and bat stars for example
are highly predatory, require uncommon amounts and frequencies
of food, and are generally unsuitable for any but the
absolute largest home aquaria (over 300 gallons), like
this temperate cnidarian predator, Dermasterias imbricata.
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It's easy to underestimate the need for
small frequent feedings (three to five times weekly) in a
sea star's diet. It's even easier to underestimate the need
to target feed these creatures at all. We must consider the
not-insignificant size/weight of a medium sized "Chocolate
Chip," "Red African," or Blue Linckia
starfish, for example, which is many times the mass of some
popular reef fishes that eat routinely. The size of these
animals also causes serious problems without proper quarantine
(QT) when a sick or dying specimen crawls into an inaccessible
crevice of the rockscape and begins to decay. It's not hard
to imagine what a comparable mass, like a 4 oz. package of
frozen meat or a large can of food pellets, poured into the
tank and left to rot would do to water quality in mere hours.
QT is not only for disease control, but also for screening
for incidental pests and predators carried in (flatworms or
predatory snails, for example) and the simple, controlled
acclimation of stressed, newly imported specimens under close
supervision.
We should also take some time to consider
what is "reef-safe" among new candidates. To anyone
with more than just a little experience as an aquarist, the
reality of what defines "reef-safe" is better-appreciated.
Ultimately, there is no such organism from a wild reef, for
display in your reef tank that is purely "reef-safe."
Put another way, everything on a reef eats something else
on the reef! Thus, the definition of whether a given organism
is "safe" or not for your tank truly hinges upon
whether or not you personally like or dislike whatever it
eats. To illustrate this point, to the aquarist with a dreadful
nuisance algae problem, an urchin mowing through the tank
eating hair-, macro-, and coralline algae is like is a blessing.
To another aquarist without hair algae, simply losing his
corallines or desirable macros to the urchin, the grazer may
be deemed "not safe."
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Asterina sea stars have been accused, unfairly
at times, for preying on coral tissue. While some individuals
appear to eat some desirable reef invertebrates, the
problem may be a simple matter of an opportunistic predator
adapting to a change in the available, preferred foods
(worms, algae).
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Returning to our example of the common,
small Asterina species found in some reef tanks, these
sea stars in recent years have suffered, unfairly I might
add, the reputation of being risky or just plain un-safe in
the reef. This is interesting because for many years prior
to that, they were not only regarded as harmless, but beneficial!
What happened? Did they all change their voter registrations
overnight? No, the answer really is quite simple. It also
explains why some other "controversial" reef invertebrates
have contradictory reputations like Mithrax/Mithraculus
crabs. Many such creatures are opportunistic feeders. While
they favor one type of prey that is convenient or popular
to us, like sand bed worms, brown diatoms or bubble algae,
they will adapt to eating other food items following the reduction
or absence of a preferred food item. Thus, the reef keeper
with a persistent growth of microalgae in a garden reef display
will likely have less trouble with misbehaving omnivores than
another aquarist with an aggressively skimmed and scrubbed
tank that supports little growth of the matter. In a phrase,
the hungrier that a so-called "reef-safe" creature
gets, the less "reef-safe" that creature becomes.
In the case of Asterina, many years ago during the
bare-bottomed, nutrient poor Berlin style era of reef keeping,
reef husbandry with early protein skimmers and limited nutrient
export processes was not as efficient as it is today; diatoms
and other nutritious growths grew quickly in our tanks. And
Asterina were not considered un-safe by hobbyists.
Summary of keys to success with Sea Stars:
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Identify the species, needs and suitability
of a candidate before purchasing. Know the
natural habits and habitat (soft substrates, hard substrates,
opportunistic feeder, carnivore, etc.).
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Be strategic on selection: avoid impulse
purchases, seek Ophiuroids among the most suitable stars.
Avoid Crinoids, and resist keeping Asteroids casually
or in young or smaller aquaria (less than 1 year old or
<100 gallons per sea star).
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Quarantine all new acquisitions to
screen for possible pests and predators, to acclimate
and stabilize newly imported specimens in the confines
of close quarters, and to concentrate feeding opportunities
to establish a stronger specimen, spare the display from
serious risks to water quality in case of a weak specimen
dying in the recesses of the rockscape.
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Target feed most species several times
weekly (smaller, more frequent feedings are always best).
In conclusion, I simply wish to re-emphasize
that most starfish we encounter in the aquarium trade are
not so opportunistic, if even opportunistic at all, as to
be able to survive in aquaria without special attention paid
to their feeding and other husbandry requirements. By isolating
new acquisitions, addressing special requirements, and not
underestimating the needs and merits of keeping starfish in
marine aquaria, we can significantly improve rates of survival
and success with these fascinating creatures.
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