Good question. I’ll try to
answer that (actually I’ll try to help you answer that).

The hobby has evolved heavily during the past two decades. One
of the trends that I have frequently noticed is the increased
emphasis on cohabitant relations. This trend is leading away from
the “can I keep this alive” attitude of the past. In my
opinion this is a great trend for the hobby to see.

The idea of what is “reef safe” has come about as
aquarists have become more adept to keeping marine organisms. No
longer worrying about general tank set up and care, modern
hobbyists are now focusing their attention on what creating
ecosystems which continue to develop and expand. They are all to
be commended for these efforts.

Flame angels are typically considered reef
safe. Most pygmy angels are well suited for the home aquaria
and rarely disturb coral tank mates.

However, with the development of complex (and usually
expensive) ecosystems comes greater concern. It is generally safe
to say that hobbyists don’t want to purchase an organism that
will destroy/eat/kill/poison/harass other tankmates. Thus the
question that people ask before purchase “is it reef
safe?”.

Large wrasse such as this Harlequin Tusk
will feed on large shrimp and invertebrates in the aquarium.
Meanwhile smaller wrasse are generally considered reef safe as
they tend to only eat micro crustaceans.

Unfortunately we can not answer that question without first
knowing what “reef safe” means. The definition of which
is dependent upon the person you ask. This gradient goes from
“all fishes and invertebrates are eating the reef and are
not reef safe” à “most things on a reef are not reef
safe” à “most things you find on a reef are safe”
à “all reef fishes and invertebrates are part of the reef
and all are safe”. The general guiding factor here is if you
feel that feeding on the reef is part of the reef, or if that is
damage to the reef. Rather than dwelling on this further, I would
rather get into some examples and categories of aquarium fishes.
I’ll tackle invertebrates later.

Fishes that eat coral

If a fish eats coral is it reef safe? Again it depends on whom
you ask. Most aquarists draw the line here and say animals that
eat coral are not reef safe and do not belong in their aquariums.
The majority of aquarists are careful to avoid such species, they
are not collected nor imported heavily because of the lack of a
market for such items.

Large angelfish are best kept out of the
reef tank. These angelfish are known to feed on
sponge, and also on coral polyps.

Lionfish are considered by many hobbyists to
be completely reef safe. Although they do not feed on coral
they will eat small fishes and invertebrates if they are
present.

Fishes that nip at coral

This category of fishes is generally perceived in a similar
fashion to those that simply do eat coral. There are many
hobbyists who aren’t bothered by a fish nipping at an
acropora colony now and then. To them, this is just a natural
part of having a marine tank with beautiful fish and corals. Of
course we have all met that friend who is willing to tear down
their entire aquarium to catch one troublesome fish that is
nipping at polyps. Often times competition from highly stocked
tanks, a lack of macro algae, and competition for limited food
influence these fishes to look for other food (in this case
coral) sources.

Copperband butterflies were historically
considered to not be a reef safe fish. However today many
hobbyists consider these fish to be beneficial to the home
aquarium.

Fishes that eat fishes

This category of fishes is not heavily discussed. Most fishes
purchased for the home aquarium are known to be what we call
“community fish” meaning they cohabitate in peace with
other fishes. Fishes that do not fit into this category are
typically known by consumers as “aggressive fish” that
belong in aquaria with other large and non-peaceful fishes. Very
popular in their own regard, aggressive fishes are typically not
misplaced or used in reef aquaria.

Eels are best left out of the reef
tank. Their need for specific rock structures,
aggressiveness, and ability to eat tank mates usually precludes
them from the average hobbyist reef aquarium.

These sea stars are often accused of eating
small fish in the home aquarium. While that may or may not be
true, most hobbyists still consider them to be beneficial in
removing waste products in the aquarium.

Fishes that eat invertebrates

This category is the most difficult for me to assess. I feel
quite confident in saying that all marine fishes eat
invertebrates. In fact I’ve yet to find a fish that
didn’t want live mysis shrimp and copepods. However, mobile
invertebrates (crabs, shrimp, worms, snails) all live in harmony
in the reef aquarium. Needless to say most aquarists keep
invertebrate eating fishes without worry of losing their
ornamental invertebrates. Therefore I guess to classify these
fishes we need to assume we are talking about fish that will not
only eat microcrustaceans but will also consume larger
species.

Pufferfish make excellent reef aquarium
fish. That is unless you plan to keep small invertebrates or
clams. A clam like the one pictured here can be a quick meal
for many pufferfish. In regards to corals and polyps,
pufferfish fair well and can be kept with corals in
harmony.

Squirrelfish often eat small invertebrates
in the home aquarium. However they do not bother corals and can
be found in several beautiful display tanks.

Fishes that eat algae

These fishes are universally considered to be reef safe fish.
In fact they are often recommended and publicized as useful
inhabitants to reef aquaria. Of personal note, the recommendation
of such fishes is worrisome to me, as I fear the overgrazing and
lack of macro algae that is often observed in home aquaria. None
the less these fishes are quite popular and suitable for home
aquaria.

Rabbitfish are excellent reef aquarium
fish. These fish serve a very important purpose of
grazing on algae in the home aquarium.

Similar to Rabbitfish, the Tangs are also
excellent reef aquarium fish. Some tangs like the Yellow Eye
tang shown here are very hardy and make excellent tank mates.
Other tangs like the Powder Blue are sensitive to water quality
and should be left for the more advanced hobbyists.

Fishes that only eat prepared foods

Don’t kid yourself, these fishes do not exist. It is true
that many fishes readily accept prepared foods, but to think that
they are obligate prepared feeding fishes is delusional. Fishes
are adapted to eating certain foods in natural settings, and will
certainly eat those items in captivity (usually meaning
micocrustaceans).

Conclusion

While guidelines certainly exist on fish species more or less
likely to be successful in the marine aquarium, deciding if
something is reef safe to you personally is the key. For many
aquarists losing a coral polyp here and there is no big deal. To
other aquarists complete capture and removal of a fish seen near
a prized coral is necessary. In my years of experience I have
come to the final conclusion on what people consider to be reef
safe and non-reef safe. If it eats something you have plenty of
or don’t care about, it is reef safe: if it eats something
you have to pay money for it is not reef safe.

Author Information

Adam Blundell M.S. works in Marine Ecology, and in Pathology
for the University of Utah. He is also Director of The Aquatic
& Terrestrial Research Team, a group which utilizes research
projects to bring together hobbyists and scientists. His vision
is to see this type of collaboration lead to further advancements
in aquarium husbandry. While not in the lab he is the president
of one of the Nation’s largest hobbyist clubs, the Wasatch
Marine Aquarium Society
(www.utahreefs.com). Adam
has earned a BS in Marine Biology and an MS in the Natural
Resource and Health fields. Adam can be found at
[email protected].