that a single adult boxfish can contain as much as 50
to 100 mg of crude toxin. Boxfishes are not thought to
be susceptible to their own toxin; boxfishes found dead
in a tank “post nuking” may have died of something
else that stimulated toxin release or been killed by the
ammonia spike that resulted from the “mass execution”
event in the aquarium. There is evidence that boxfish
toxin may work on receptor sites on the gills of their foes
(known as PHN-binding sites)—it turns out that these
sites are not present in the boxfishes, which may explain
their tolerance to the toxin. Fortunately, even though
a boxfish can be lethal to its tankmates, these episodes
are very rare if precautions are taken. In all my years as
a marine-fish keeper, as well as working in the pet fish
trade, I am only aware of half a dozen cases of individu-
als “nuking” a tank (more on this later).
Boxfishes are gonochoristic—that is, they are born as
either males or females and do not change sex. Members
of the genus Ostracion exhibit extreme chromatic differ-
ences between the sexes. In fact, for many years it was
thought that the male and female color forms represent-
ed distinct species. Some of the other boxfishes are also
sexually dimorphic. In some species, males are smaller
than the females or have thinner bodies. All the boxfishes
studied thus far are haremic. One or more non-territorial
females roam over ill-defined home ranges in the larger
territory of a dominant male. Subordinate males do not
stake out territories, and live within the defended area of
the more dominant males.
The Spotted Boxfish, Ostracion meleagris
(male shown), is a small member of the clan
that only grows to about 6 inches (16 cm) but
is also most likely to “nuke” an aquarium.
BOXFISH SPECIES WITH MAXIMUM SIZESSmaller Species
Thornback Cowfish (Lactoria fornasini)
15 cm (5.9 inches)
Spotted Boxfish (Ostracion meleagris)
16 cm (6.3 inches)
Striped Boxfish (Ostracion solorensis)
11 cm (4.3 inches)
Whitley’s Boxfish (Ostracion whitleyi)
16 cm (6.3 inches)
Larger Species
Honeycomb Cowfish (Acanthostracion polygonius)
48 cm (18.9 inches)
Scrawled Cowfish (Acanthostracion quadricornis)
48 cm (18.9 inches)
Spotted Trunkfish (Lactophrys bicaudalis)
45 cm (17.7 inches)
Smooth Trunkfish (Lactophrys triqueter)
30 cm (11.8 inches)
Longhorn Cowfish (Lactoria cornuta)
46 cm (18 inches)
Yellow Boxfish (Ostracion cubicus)
45 cm (17.7 inches)
Humpback Turretfish (Tetrasomus gibbosus)
30 cm (11.8 inches)