The term ‘clownfish anemone’ is an incorrect description, but it describes them well enough. These are the anemones that clownfish use as a home. Probably nearly everyone, aquarist or not, has seen the amazing sight of an unharmed clownfish within the stinging tentacles.
Some of these anemones are in fact called the Carpet Anemone (Stichodactyla gigantea), the Pink Anemone (Heteractis malu), the Bulb Anemone (Entacmaea quadricolor), and Ritteri Anemone (Heteractis magnifica). There are others.
The anemone is more likely to settle well into an aged aquarium. In other words, a system that has been running for quite a few months as this normally means that it is stable. The bio-filtration has settled down and the rock structures have a population of some algae and tiny life. I know of one retailer who will not sell one of these anemones to an aquarist unless his/her system is at least 9 months old.
There are other points to note. The first is the often repeated one – water quality must be high. It should also be noted that lighting needs to be correct as the anemones contain symbiotic algae (zooxanthellae). In a reef aquarium this is normally not a problem as the corals have the same requirement, but in a fish only system (provided the water quality is high enough) the lighting might need alteration.
When purchasing an anemone be sure that there aren’t any signs of damage, particularly on the foot. Sometimes there is damage in that area as getting the anemone off its rock is very difficult. It is much better if there is a rock attached. It is a good idea that when the anemone has been chosen at the retailers, research the natural colour. If the anemone is not this colour, but pale white (unless its meant to be white) or translucent, don’t buy it.
Also these anemones can grow large. I had one which completely outgrew my aquarium and I had to sadly let it go complete with clownfish (I couldn’t bear to separate them). Research will indicate the chosen anemone’s potential size.
Make sure pump intakes and overflows are guarded. If the anemone does wander as it might (see below) it could get sucked into a pump or overflow and be badly damaged.
Placement in the aquarium is very important. If the anemone is not happy with its position it is likely to wander until it is. Much to the irritation of the aquarist it may decide the perfect spot is on the front viewing glass, or somewhere else that is inappropriate.
The anemone should be placed fairly high on the reef, even on the top. The foot should go in a hole or crevice, as the anemone should be happy with that from a defensive point of view – they can contract into it, at least to an extent for protection. If there is a rock attached already to the anemone, don’t try to take it off. The anemone’s grip is very strong and damage to the foot is likely. Just make a hole for the rock to go into, leaving a suitable crevice or such above as described. If there isn’t a rock attached, the anemone should be placed into a crevice etc and given time to attach. To facilitate this circulation pumps may need to be turned off for a few hours (not the bio-filters if these are pump driven). The anemone should attach quite quickly – much more rapidly than a coral.
So the anemone is in place and has adequate lighting. There is one more requirement, and that is water movement. The surface of the anemone should be disturbed by random water movement (that is, not continuously one-directional). The flow need not be powerful, but moderately so. This can be judged by the tentacles when the anemone is expanded, they should wave about like flowers in a moderate breeze.
It seems anemones are fussy. Perhaps they are, but once settled they will give little trouble if water and lighting quality are maintained.
Feeding couldn’t be more simple. It is reported that the anemones can survive but not grow and multiply from the products of the zooxanthellae only, they need additional food. They are well equipped for this, as they have stings in the tentacles (nematocysts) which are fired into the prey when stimulated and poison is delivered. The food can be a small part of a frozen fish etc, the normal aquarium food used for feeding other livestock. The food should be cut fairly small, defrosted (not in a microwave, use seawater or R/O water) and placed in the tentacles. The anemone will move it to the mouth. If there is a resident clownfish it may well steal the food, even though it is too big for the fish to eat. In this case, place the food as close as possible to the mouth of the anemone and ensure the tentacles take hold. Recalling my clownfish, it would even do its best to pull the food out from the anemone’s mouth. It was always interested in the anemone’s food, even though it had been purposely fed beforehand. Don’t overfeed the anemone, once or twice a week should suffice.
Clownfish will not always take up residence in an anemone, much to the aquarist’s disappointment. Some aquarists declare that this is because they are tank bred, and do not recognise the anemone. I don’t dispute this, but what of the young in the wild, they have no formal education that ’this is an anemone’ but find one nevertheless. In addition, tank bred clownfish are known to adopt an anemone, it has been reported often. Perhaps it is instinct.
I would suggest that failure to adopt an anemone could be because it may be the wrong type of anemone. It is known that different clownfish favour different anemones. In view of this I have added a link at the end of the text so that a check can be made.
Bear in mind when considering an anemone that they are equipped to catch prey. The fish in the aquarium are prey for the most part as far as the anemone is concerned. This could occur when a fish swims close to the anemone and gets ‘blown’ in by the water currents. I recall having my heart in my mouth a good few times at how close some fish ventured, but fortunately a mishap never occurred.
An anemone, particularly if it has an attendant clownfish or two, is a really interesting addition to the aquarium. They need good husbandry and they could get large!