I often get asked what is the food of anemones. Do I have to feed my anemone? Like in hard corals, anemone tentacles too contain zooxantelle, which alongside the byproducts of their photosynthesis cover the most part of carbon requirements. Because of their symbiont algae these sea anemones are limited in nature to areas of low water and very abundant in light. But they too have to capture preys in addition to that. Many species feed on plancton, other ones prefer small fish instead. I personally feed all of my anemones with mollusk pulp. Once per year I usually buy a bag of mollusks and I then freeze them. Every 14 days I take one mollusk per specimen and I let it unfreeze in warm soft water, then I’ll accurately rinse it with more soft water and I’ll remove the pulp from the shell. With the help of a plastic claw I am accurately able to feed anemones in a targeted way. It is surprising, how rapidly these animals will retire at contact with such a piece of food, to protect the “prey” from eventual diners, promptly swallowing it. It seems anyway that not all nurtured reef fishes have a great deal of respect for a sea anemone’s tentacles. My yellow surgeon (Zebrasoma flavescens), for example, will regularly go as far as subtracting food from the tentacles of the two “sticky” Cryptodendrum adhaesivum, at least when frozen artemia are featured on the menu. It simply removes those that are glued to the tentacles. Indeed, I cannot believe that such a fish could be able to expose itself, by doing so, to a particular risk, since the anemone should not be able to, at least partially, capture such a large surgeon fish, even if there are such reports every once in a while. An anemone may be able to capture fish of such size only if the latter are badly injured and therefore already on the path to death. It seems like even sea urchins have fallen prey to carpet anemones. If this turned out to be true, it would probably be due to an insufficient food supply, modifying nutritional behavior.
It is stated that anemones should be able to reproduce not only by sexual means, but also asexually through split. This circumstance has been proven for Heteractis magnifica and also for Entacmaea quadricolor. The latter species goes as far as easily proving this characteristic true if water values are in check. Even environmental changes induced by the anemone’s moving in another aquarium can provoke a split. After introducing an E. quadricolor in my 1,000 liters aquarium, as early as the next day I noted that something was wrong already. The anemone was dangling weak and flattened from its rock (which I moved alongside the animal), with no reaction. The day after I could not believe my eyes: in my aquarium, destined to become a tank for many different species of anemone, I had three E. quadricolor. The size was imposing. It was to be suggested that through split spring polyps could be formed, with a combined size equal to that of the mother polyp. But the mistake was impressive! The animals were so bloated with water, that I now had three huge anemones with a combined diameter doubling that of the original specimen! After three days, each had reached the dimensions of the original mother polyp, and in the meantime the aquarium was full of these anemones! I associated the strong reproduction of my E. quadricolor to the regular and abundant administration of mollusk pulp, even though it normally happens once every two weeks. I often had the opportunity to learn that anemones, after many different food administrations, have an intense development only to split shortly after.
Maintenance of sea anemones in a reef aquarium is not, based on my experience, particularly difficult. However, it requires some precautions to take with aspiration piping and strong circulation pumps, and in case of many different outflow openings, which develop a strong backwash. If adequate protection of these openings is not accomplished, then passing anemones can easily be sucked in, causing accidents. A small aspiration grid, which the anemone is able to fit inside its body structure, is not sufficient. A solution to the problem would be to make it longer than the anemone itself. This way the animal is not able to completely cover it and to be subjected to the entire aspiration. But if an “accident” did happen, anemones of several different species feature extraordinarily developed regenerative properties, that is, with adequate feeding conditions. If the body column with the foot and the oral opening are intact and the wound is limited to only the tentacles or to the edge of the oral disc, a sea anemone is perfectly healthy only after a few days.