NEWS105
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extremely poor in nutrients and
suspended matter, and hence clear,
though the water does filter the light. At
depths ofmore than 10m all visible light
colors are in fact still present, but there is
already a noticeable shift towards the
blueendof the spectrum. Inaddition, less
than10%of the light fallingon thewater’s
surface penetrates this far. Hence in
aquaria where the lighting capacity is
designed for light-hungry small-polyp
stony corals, it is necessary to site large-
Largepolyps – large appetites?
There ismuch violent controversy among
marine aquarists as to when, and indeed
how,LPS shouldbe fed.Byday thepolyps
of some species remain closed, as in the
wild the plankton density increases
considerably at night. As passive feeders
that can’tpursue their food,coralshave to
make dowithwhat drifts into their arms.
By day numerous predators on corals (eg
butterflyfishes) are out and about, so it is
Euphylliaancora
Euphyllia
sp.
polyp stony corals in rather shadier
positions. The same applies to current. At
this depth there is far less of the
turbulence that prevails near the water’s
surface and to which numerous reef-
builders must adapt. Hence current
pumps shouldn’tbeaimeddirectlyat LPS,
as theywill tolerate thisonlypoorly.
safer and better for the polyps to open
only at night, a behavior that these
species also retain in theaquarium.
As already mentioned, there is no single
viewamongaquaristsas towhichmethod
ofmaintenance is thebest. Some achieve
outstanding success in extremely
nutrient-poor water (phosphate not
measurable, nitrate less than 3 mg/l),
while others find their large-polyp stony
corals rapidly die off under such
conditions. On the other hand good
results are regularly reported in
somewhat more nutrient-rich water and
with varied feeding of the fishes. In such
cases the corals always receive some fall-
out from the food intended for the fishes.
It is probably no coincidence that in
aquaria where frequent feeding with
small portions takes place every day and
the diet is as varied as possible, not only
the fishes but also the large-polyp stony
corals thrive splendidly.
What foods?
Easier said thandone, as the sayinggoes,
Catalaphyllia jardinei
Fungia
sp.
