and taking it in. If possible, feed entire animals, not just
muscle flesh—the anemone needs and can digest the additional nutrients in the viscera and skeletons.
Unless the anemone is quite small, it is necessary to
specifically feed it to ensure that it eats enough food. Although in nature animals can survive on the particulate
matter in the water, it is typically far greater than is ever
found in aquaria. Aquarium anemones will certainly benefit from brine shrimp, mysids, or extraneous foods from
fish, but such foods in aquaria are generally present in
insufficient amounts for anything but a periodic snack.
The amount of food needed will vary with the species and the size of the animal but is often quite a large
amount. As an example, a mature Stichodactyla haddoni I
once had was fed about one or two heaping tablespoons
of diced lance fish or cut-up smelt every other day or so.
Anemones rid themselves of excess or indigestible food
as feces after a few hours. Defecated material should be
removed as soon as it is noticed. It might be a long time
between these events. In the seven or eight years I had
that S. haddoni, to the best of my knowledge it defecated
only twice although it completely consumed everything
offered it. As an example, it captured a 4-inch ( 10 cm)
long raccoon butterfly fish that I put in to eat Aiptasia.
The entire butterfly fish was eaten, no remains were ever
egested, and the animal ate its normal mass of food the
next day. Burp!
Fecal material is indigestible food, but it is not waste.
If it is not removed it will foul the tank since bacteria
and other animals will eat it, but it won’t kill them outright. The actual waste material is ammonium ion, often
called ammonia by aquarists. As most aquarists know,
true biological wastes such as ammonium ion are highly
poisonous. Typically, the amount of ammonium released
by a healthy zooxanthellate anemone is unnoticed and
undetected without special testing apparatus, even if the
animal is well-fed. The host’s zooxanthellae will generally absorb all of the nitrogenous waste and convert it into
some algal proteins or byproducts and recycle it back to
their host. Feeding a healthy zooxanthellate anemone is
effectively a waste-free process.
The best measure of sufficient feeding is growth or reproduction of fully mature animals. If the aquarist wants
their anemone to remain small, it should initially be fed
enough to grow until it reaches a size where more food is
required for it to grow further. Do not increase the food
volume at this point, and the animal, although small, will
remain healthy. Care needs to be exercised so the animal
doesn’t slowly start to shrink, as this may indicate that a
problem such as competition with another animal, is interfering with the anemone. In such a case, the food
will need to be increased.
Ronald L. Shimek, Ph.D. is the author of A PocketExpert
Guide: Marine Invertebrates (Microcosm/TFH Professional Series, 2004).