The young Yellow Boxfish has an almost perfect box shaped body which becomes more
elongated as it grows older. It also changes from the yellow or cream color when
young to different colors when older, mostly yellow-green. The spots also change
from dark-blue in the young fish to white with blue rings in the adult. The body is
enclosed in a bony structure covered with a thin layer of skin with fins sticking out and
no spiny dorsal fin.
Boxfishes belong to the Tetraodontiformes order which also includes puffers,
porcupinefish, and triggers. Boxfishes belong to the Ostraciidae family.
Boxfishes are also commonly called cowfishes and trunkfishes (for example, the popular,
Long Horned Cowfish - Lactoria cornutus).
Although many of the offerings in the fish stores are tiny, some as small as a dime,
these fish can grow to 15-18 inches, therefore a large aquarium is recommended - 100
gallons and up. Boxfish like to hide, so hiding places should be offered and will
provide a retreat from any perceived danger. The Yellow Boxfish requires no special
lighting or temperature, very good tank conditions and water parameters are needed.
Strong water movements cannot be handled by the young boxfish as they are slow
swimmers. Make sure they can't get sucked into any powerheads or filters you may
have. They should be kept in Fish Only tanks as they will pick on (eat) soft corals,
tube worms, etc. in reef tanks. The Yellow Boxfish should never share an overcrowded
tank or have aggressive or fast moving tankmates. The Yellow Boxfish will swim all
levels of the tank (top, middle, bottom).
According to Mark Taber's Survey On Fishkeeping (from Albert Thiel's website (http://www.athiel.com) and posts to
rec.aquaria.marine.misc and rec.aquaria.marine.reefs newsgroups) which quoted Frank M.
Greco's list of fish unsuitable for captivity, the Yellow Boxfish should not be kept in
the home aquaria. The fact that boxfish are so prone to ich was the reason for their
being added to the list. Per Mr. Greco, "...a survey I did of local area
wholesalers found that a minimum of 30% and a maximum of 100% of these fishes died.
Necropsy found that most, if not all, of these animals were infested with Amyloodinium and
Cryptocaryon. The degree of survival past the wholesaler/shopowner portion was small
as well, if memory serves. And, these fishes tend to be copper sensitive to boot,
IME (in my experience) with them. So utilizing copper on these fishes during
quarantine seems to cause more problems than it's worth. Many die from it and those
that do not are never quite right afterwards. Malachite green is a good substitute,
but it's just not as effective as copper."
While conversing with Mark and Frank to obtain their okays to quote, Frank requested
that I also add the following to the article. "...you should also note that my
designation of this fish as difficult is, at best, a subjective one. My reasonings
behind listing this fish thusly are, IMO (in my opinion), sound ones. But, as in
almost all cases, my experiences may not be the same as those of others. It is
important that this be made known. My listings are not absolute, nor should they be
taken that way."
Thanks go to Mark Taber (email@example.com)
and Frank M. Greco (pHrank2139@email.msn.com)
for their permissions to quote.
Foods & Feeding:
Before bringing your boxfish home, make sure it is eating at the store. You must
be 100% sure your fish is eating. A boxfish that isn't eating may already be
stressed and any stressed fish won't survive long, especially a boxfish with their ability
to release toxins and susceptability to Cryptocaryon, etc. Larger and older fishes
are harder to start feeding than younger ones.
Because they are naturally slow moving, shy, and rather clumsy, the Yellow Boxfish may
very easily be outcompeted for food by tankmates, especially if the tankmates are
aggressive fish. It is vital that you make sure your boxfish is eating
regularly. If you keep your boxfish with more aggressive fish, it is best to feed
them first, then concentrate on feeding your boxfish. That way, competition for food
will be less.
The Yellow Boxfish is an omnivore and will eat all kinds of live, frozen, flake, and
Small fish (dime size) can be offered live and frozen brine shrimp as well as cubed
frozen food like Ocean Nutrition's Formula I and II (thawed or not, depending on how well
it is taken). If they refuse the Formula I or II, you may try adding it at the same
time as the brine shrimp and they may try it and you can slowly decrease the brine shrimp
offered until they have switched. As they grow, they will develop a huge appetite
and will even "beg" for food (swimming to you whenever you near the tank).
Overall, a variety of foods is best, including seaweed (Ocean Nutrition's Seaweed Selects
or nori (dried seaweed used to wrap sushi - unseasoned). As in last month's Kole
Tang article, the seaweed can be offered in a suction cup clip or rubberbanded to a piece
of rock or tank ornament.
They are such slow movers that they are easily caught by hand. They move
awkwardly using their side fins and the tail fin only in case of emergency or to get
food. It is common for them to "sit" still in one spot for very long
periods of time.
This fish can be extremely dangerous to other tankmates and itself. If threatened
or stressed, they can release a toxin into the water which will kill everything in the
tank, including themselves. Invertebrates are not safe from this toxin either.
They may also release this toxin on death. If your boxfish looks diseased, stressed,
or on the brink of death, it is vital that you remove it to a quarantine tank. A
boxfish close to death will be lethargic and will experience rapid color fading in the
minutes or hours before death. If one dies in the aquarium, remove it immediately,
every second counts for the life of whatever else is in the tank. Hobbyists report
all livestock in a 65 gallon tank dead in an hour and animals dying within seconds of a
Because of this ability to release a toxin, the yellow boxfish, and boxfish in general,
are usually considered to be for the more experienced hobbyists as they are better suited
in maintaining a stable environment, etc. Although it has been reported that they
will rarely release this toxin, it is still a possibilty, and one best kept in mind when
considering purchasing this fish.
If the tank has been hit with the toxin, hobbyists suggest the following to help combat
it's effects: remove fish to quarantine tank, perform 100% water change, make sure
protein skimmer is running at top efficiency, add activated carbon to filtering system,
when adding fish back do not put the water they are in back into the tank, another water
change after system stabilizes (a week or so). Removal of the toxin from the tank is
not entirely possible as it will settle into live rock, ornaments, bio bed, filters,
etc. Using this method may prevent the death of your biological filter as the toxin
is reduced and further dilution is possible through the subsequent water change(s),
protein skimming, and addition of carbon.
Some reports note that this fish may or may not be aggressive towards it's own kind,
therefore, care should be taken when adding a new boxfish into a tank with an established
boxfish. I cannot say for certain if this is true or not, but it was found in some
of my research. Most hobbyists mention the Yellow Boxfish's gentle nature (even so
far as taking food from the hobbyists hand and being petted), but I couldn't find anyone
having kept more than one in a tank so I cannot say if this is true or not.
Boxfish develop skin diseases easily (Cryptocaryon, etc.) and are very difficult to
treat. They cannot be treated with copper, which causes some controversy among
hobbyists with some reporting success treating with copper, others report death, I prefer
to go against using copper as my research shows more against than for. Why take the
chance with an animals life? Do not give your boxfish a freshwater bath as is
sometimes recommended as a treatment, as a matter of fact, avoid removing your boxfish
from the tank as it will just stress them and a stressed boxfish may release it's
toxin. I would only recommend removing a boxfish, as I noted above, when already
stressed, diseased, or on the brink of death.
Although they will survive nicely in normal water parameters, it is important to keep
those parameters under control. No ammonia, nitrites, etc. If you let these
parameters slip, you are asking for an outbreak of disease.
Boxfish will not tolerate cleaner wrasses well, but hobbyists report them allowing
themselves to be cleaned by shrimp. They don't like being cleaned by wrasses because
they don't have scales. Scaleless fish can be injured by cleaner wrasses who will
harrass them long after there is anything left to clean and since boxfish swim so slow
they can't easily get away.
Store: From $15 to $40 with a 12 inch one going for $80. Two stores were checked in Queens, New York for prices.
Online: From $10 (small) to $14 (large). Two online sites were checked to obtain these
This fish is only occassionally available through local fish stores, but is usually
more available via online services.