The global trade in marine ornamental species

From ocean to aquarium
A branching coral ready for export.
abundant corals in trade, partly because these species
survive poorly in captivity and so must be regularly
replaced. Aquarists have reported that, in aquaria, these
species usually deteriorate and eventually die within a
period of three to six months. A regular feature of
aquarium specimens is unexplained stunted growth.
Corals are also easily damaged during collection and are
susceptible to disease 74 . Heliofungia is one of the oldest
species in the history of the coral trade 181 . Like Goniopora,
Heliofungia has a poor survival record in aquarium
conditions as it is very sensitive, can easily be infected by
bacteria, and colonies can quickly die due to changing
ultraviolet (UV) light conditions 181 .
Overall, mortality rates of coral pieces in home
aquaria are fairly high, with one study concluding that
complete mortality occurs after 18 months 182 and others
registering up to 76 per cent mortality in hard corals kept
in aquaria for more than 18 months 183 . Plerogyra spp. and
Catalaphyllia spp. registered lowest mortality rates, 54
per cent and 60 per cent respectively, whilst Heliofungia
spp. (100 per cent), Goniopora spp. (95 per cent) and
Tubastrea spp. (100 per cent) registered the highest
mortalities 183 . Nonetheless, species in these genera are
commonly traded. (See Tables 7 and 8, pp 23-24.)
Recent advances in the maintenance of corals
in aquaria, through improved and more affordable
technologies, may lead to an increase in coral longevity in
aquaria. Further improvements in coral husbandry
techniques and the wider dissemination of information on
how to keep and maintain coral species (especially as more
information is available over the internet) should also
minimize coral mortality.
Soft corals and sea fans
Most of the common traded species of soft corals such
as Cladiella, Clavularia, Cespitularia, Lobophytum,
Nephthea, Sarcophyton, Sinularia and Xenia possess
zooxanthellae. They generally do not require plankton or
special foods and thus are fairly easy to keep in aquaria.
Described as hardy species, they are able to survive
stress during collecting and shipping and to heal wounds
as well as regenerate tissue relatively fast. Once
established they tend to grow quickly and are regularly
observed to propagate asexually. Cutting off their
branches may even be necessary to prevent overgrowth in
aquarium conditions. Their suitability as aquarium
specimens may be related to the fact that they are more
tolerant to fluctuations in water quality (although many
soft coral species will not tolerate salinity levels of less
than 30‰ 181 ) than other species of corals 64 . Notable
exceptions to this are the more sensitive species Anthelia
spp., Cespitularia spp. and Xenia spp., which do not fare
well after fragmentation, are vulnerable to transport and
sudden changes in aquarium conditions 181, 184 . Nevertheless,
they grow fast once established.
Unfortunately, most of the more colourful and
beautiful soft corals do not contain zooxanthellae (i.e. they
are non-photosynthetic). Azooxanthellate soft corals, for
example Dendronephthya spp. (one of the ten most traded
soft corals, see box p 25) and Studeriotes spp., cannot
easily be propagated and are extremely difficult
to maintain in aquaria as they are entirely dependent
on filtering particles and absorbing dissolved nutrients
from the water column 64, 181, 184 . Due to these dietary
requirements, these species usually die within a few weeks
under aquarium conditions. Scientists and experts in the
aquarium industry strongly recommend that people do not
collect or keep azooxanthellate soft corals in captivity,
unless they are the subject of scientific research 185 .
Azooxanthellate sea fans such as Ctenocella spp.,
Echinogorgia spp., Ellisella spp., Euplexaura spp. and
Lophogorgia spp. are just as difficult to maintain. They
attract aquarists’ interest due to their bright red or yellow
colour, but show poor survival rates in captivity. On the
other hand, zooxanthellate species such as Gorgonia
spp., Pseudopterogorgia spp. and Rumphella spp., often
brown to yellowish brown, are fast growing, their
maintenance in aquaria is fairly straightforward and they
can be easily fragmented for propagation purposes.
POST-HARVESTING MORTALITY
There are many factors that lead to post-harvesting
mortality, such as physical damage and use of chemicals
during collection, poor handling practice and disease.
Even when collected in an environmentally sound manner,
aquarium organisms often suffer from poor handling and
transport practices resulting in stress and poor health of
marine individuals 30 . Accurate figures of post-harvesting
mortality are not available due to the sensitivity of such
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