Page 208 - Encyclopedia of Aquarium and Pond Fish, 3rd Edition

206 MARINE FISH: SETTING UP THE TANK

Lighting considerations

Lighting the marine aquarium is both an art and
a science. In an ideal setup, the light should appear
natural and should enhance the colors and forms of
the tank occupants, but it must also be of the correct
intensity and quality to sustain life. Achieving this
balance requires some planning, especially in reef tanks.

The marine fishkeeper is presented with an apparently
bewildering variety of lighting alternatives; choosing the right
one depends largely on the types of marine organism housed
in the aquarium. Most fish are tolerant of a wide range of
lighting conditions, so for a fish-only setup, it is usually Lighting arrays or
enough to provide lighting that displays the fish most effectively. hoods often include two
Light levels should not, however, be set too low, or the fluorescent tubes—one
creating good viewing
growth of undesirable red/brown algae will be encouraged. conditions and the other
Lighting a reef tank is a very different matter. Many providing blue light.
invertebrates in reef aquariums, such as corals and anemones,
survive only because they form partnerships with tiny along with their hosts. In their natural setting—shallow
photosynthetic algae that live inside their bodies (see box, reefs in tropical seas—these organisms are exposed to bright
below). If the algae do not receive sufficient light, they die, light from the sun for 8 to 10 hours per day, and these
conditions must be replicated with artificial lighting if they are
to survive in a tank. Using sunlight to illuminate the aquarium
is not a viable option. Instead, special tubes and bulbs, usually
LIGHT AND INVERTEBRATES mounted in a specially made hood, are used to simulate
Certain invertebrates, such as various sea anemones, corals, and both the intensity and the quality of light falling on a reef.
some mollusks, contain photosynthetic algae called zooxanthellae in
their fleshy bodies. This is a symbiotic relationship in which the A natural coral reef has many
algae supply their host invertebrate with food and oxygen and in different zones of light. Colored
return receive shelter and take up some by-products of the animals. corals predominate in the sunlight
When a sea anemone (bottom left) opens its tentacles, the zone. Deeper down, leather corals,
maximum amount of light reaches its algal partners; the tiny anemones, tubeworms, and others are
greenish bodies of the zooxanthellae are visible in the close-up of a more prevalent. Darker areas are
coral polyp (below right). However, not all invertebrates in a marine occupied by soft corals, sponges, and
tank thrive under high light levels, and there should be suitable invertebrates that lack zooxanthellae.
retreats in an aquarium if it is to house crabs and sponges.

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