Coral - March/April 2010

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.