Host Anemones and Clownfishes: 3 Symbiotic Pairs

James W. Fatherree

In the wild, all species of clownfishes live in unique symbiotic relationships with a few species of sea anemones, and this relationship can be recreated in a marine aquarium. However, for it to last, it’s important to try to get the hardiest and healthiest anemones available and provide them with the proper long-term care. It’s also very important to choose the correct pairing of anemone and clownfish, as many clowns can be quite selective about which type they will live with.

There’s a good reason for this discernment. If a given species of clown were to attempt to enter the wrong species of anemone, it would most likely be treated just like any other food item and get stung and eaten. However, the species-species combinations can be more flexible in aquariums than in the wild. Sometimes matchups not observed in the wild occur in tanks where no normal host anemone is present. Some clowns simply make do with something else. 

Infrequently, clown-hosting anemones are offered at shops, but not all will live long in aquariums. Here, we’ll focus on three hardy and commonly offered anemones, how to choose good specimens and care for them, and which clowns are proper matches for each. I’ll start with what is certainly the most popular anemone around, the bubble-tip.

#1. The Bubble-tip Anemone (Entacmaea quadricolor)

A great choice for many anemone and clownfish pairings, the bubble-tip anemone comes in quite a few forms and colors including some fantastic red ones sold as rose anemones. This species can also vary greatly in size. Some grow to not much larger than a deck of cards across and have relatively short tentacles, while others can get huge. Extra-large specimens may grow to over a foot (30.5 cm) across and have tentacles that extend several inches. 

Entacmaea quadricolor is called the bubble-tip because its tentacles typically have large bubble-like swellings at their tips. However, these bubbles can come and go. Specimens that have shorter tentacles may not develop or retain the bubblelike swellings over time, and those with long, thin tentacles almost never do.

It has been suggested that the absence or presence of the bubbles has something to do with lighting, feeding, and/or the lack of a clownfish hanging around, but nobody is sure. What you can count on is that this is a hardy species, and many different clowns will take up residence in one.

In the wild, bubble-tip anemones host a lot of clownfish species that are commonly offered in the hobby, including the maroon (Premnas biaculeatus), tomato (Amphiprion frenatus), fire (A. ephippium), cinnamon (A. melanopus), and clarkii clownfish (A. clarkii). They’ll also host several of the less common species, such as the Barrier Reef (A. akindynos), Allard’s (A. allardi), Red Sea (A. bicinctus), orange-fin (A. chrysopterus), whitesnout (A. mccullochi), Oman (A. omanensis), red (A. rubrocinctus), and three-band clown (A. tricinctus). In aquariums, they’ll also sometimes host the percula (A. percula), false percula (A. ocellaris), Maldives (A. nigripes), and white-bonnet clownfish (A. leucokranos).

#2. The Long-Tentacle Anemone (Macrodactyla doreensis)

The long-tentacle anemone (Macrodactyla doreensis) is sometimes called a corkscrew anemone, and it has a large, flattened disc like that of a carpet anemone. However, instead of being covered with very short tentacles, it has very long tentacles that often spiral upward and out, much like long corkscrews.
It can get big too, with a disc that’s well over a foot (30.5 cm) across and tentacles that are over 8 inches (20.5 cm) long. It can be found in a variety of colors, and some are even striped. It can be an impressive-looking anemone, for sure.

In the wild, M. doreensis only hosts two clownfish species commonly offered in the hobby, the clarkii clown and the pink skunk clown. It’ll also host the Mauritian clown in the wild. In aquariums, it may host the percula clown, the false percula clown, the saddle clown, or the maroon clown, too. So, there aren’t as many species of clown to choose from for the long-tentacle anemone, but at least a few are common.

#3. The Carpet Anemone (Stichodactyla haddoni)

There are three carpet anemones seen in the hobby, all of which belong to the genus Stichodactyla, and they look very similar. All three have relatively large, flattened bodies and especially short tentacles, but S. haddoni is seen for sale far more often. I’ve also seen S. haddoni misidentified as the other two (S. gigantea or S. mertensii) on a few occasions.

S. haddoni, like the others, can easily grow to well over a foot (30.5 cm) in diameter, and it has very small tentacles that typically look like little beads that cover almost its whole disc (body/upper surface), with only a small area around the mouth that is free of them. Often, the tentacles are more than one color.

S. gigantea also has short tentacles, but they’re usually a little longer than those of S. haddoni and slightly pointed at their tips. Much more of the disc is tentacle-free, as well. However, S. mertensii typically has some tentacles that are relatively long for a carpet anemone, almost an inch (2.5 cm) in length, which are also absent in the area right around the mouth.

S. haddoni and S. gigantea have tentacles that are sticky, while S. mertensii does not. Also, the discs of haddoni and gigantea often fold up like a saddle, while those of S. mertensii usually lie flat on the substrate. With careful inspection, and maybe a touch, you should be able to figure out what’s what if you’re ever unsure.

In the wild, S. haddoni hosts a lot of clownfish species commonly offered in the hobby, including the clarkii, saddle (A. polymnus), sebae (A. sebae), orange-fin, and Mauritian clown (A. chrysogaster), as well as the less common Barrier Reef clown. And, like the bubble-tip anemone, it will also host a few species in aquariums that it will not in the wild. These include the false percula, percula, pink skunk (A. perideraion), and orange skunk clown (A. sandaracinos).

Anemone Care

In general, anemones can be more difficult to keep alive long-term than corals and such. However, if well cared for, they can last as long as anything. In fact, bubble-tip anemones are known for being prolific reproducers. So what’s involved with taking good anemone care?

First of all, water quality should be high, of course. For the three species above, it doesn’t have to be pristine, but it should be reef-aquarium worthy. Nutrients should be kept relatively low, and the pH and alkalinity should be maintained at levels suitable for keeping corals.

There should also be sufficient water motion to keep an anemone’s tentacles moving around and to prevent detritus from settling on its disc, though a carpet anemone’s tentacles don’t really move around like a long-tentacle anemone’s.

For successful anemone care, you will need to provide them with plenty of light, as in reef-aquarium-level lighting. Unfortunately, I’ve seen a lot of hobbyists try to keep anemones in what should be fish-only aquariums, sometimes with a couple of extra fluorescent bulbs. However, that doesn’t work out in the long run. Like corals, most of the tropical anemones carry symbiotic algae in their bodies that they must have in order to survive. They need adequate light to keep these algae going and to gain nutrition from the algae’s photosynthetic activities.

You don’t necessarily need a full-blown system with metal halide bulbs or superbright LEDs, but you’ll need a lot more than a few standard-wattage fluorescent tubes. If there’s not enough, you’ll get to watch an anemone slowly shrink in size over a period of weeks until it finally dies.

After good water and lighting, the next thing to take into consideration is feeding, and I attribute my own successes with anemones not just to acceptable water quality and light but also to regular feedings. Make no mistake: anemones are carnivores and should be treated as such. Sure, some anemones seem to live indefinitely without being given any sort of foods, but they’re much more likely to live long lives and thrive when fed, though you don’t have to give them something every day. Depending on your choice of species and size, you should experiment with different types of meaty foods, from brine shrimp to bits of fish, and find out what and how much it’ll eat.

You can use a turkey baster to squirt some brine shrimp into the tentacles of many anemones or a wooden stick to deliver a small bite of clam, squid, fish, etc., and you’ll find that some have food preferences. Providing a decent meal once a week is typically sufficient to keep anemones in good shape and growing. Just watch out for nasty-looking balls of goop an anemone may spit out if it’s being fed too much at one time or is being fed something it can’t or doesn’t want to digest.

Other than that, you may have to deal with some crawling. Many hobbyists have problems when an anemone won’t be still and instead decides to roam around the tank. Typically, this just means the anemone is unhappy with the spot you picked for it and is trying to find a better place to live. If you can get the positioning right in the first place, you’ll be less likely to have crawling problems. 

Specimens will also be less likely to move if they’re well lit, are getting hit with a current that’s not too weak or strong, and have a place to attach their bases, so think about these things when adding one to an established aquarium. Really, the best way to do things is to put the rockwork in place when setting up an aquarium, then add the anemone(s) before anything else. Let it/them get situated, and then start adding the other things afterward. Even if it’s a pain for a while, I’ve found time and time again that once an anemone gets situated, it tends to stay put indefinitely.

Choosing Specimens

There are a few additional considerations to think about before pairing your anemone and clownfish. For starters, don’t buy any anemone that isn’t attached to something at the shop, like a rock or the side of the holding tank, and it should be opened up with its tentacles expanded. I don’t mean you have to take it home attached to something, just that the attachment to something and expanded tentacles are signs of good health. Just make sure that the store employee is very, very careful when removing an attached anemone to bag it up.

Before getting to the bagging part, though, you should carefully examine the anemone to make sure that it doesn’t have any obvious injuries. Anemones can really get a good hold on a rock, so they sometimes end up with tears or cuts on their bases during the collection process when they are pried loose. Such injuries, even if they look minor, can lead to quick death or a long, dragged-out one.

Another important thing to look for is a closed mouth. The mouth is usually easy enough to spot, right in the middle of an anemone’s disc, and it should not be gaping open. If the mouth is open for no apparent reason, and especially if any of the anemone’s “guts” are protruding from the mouth, you shouldn’t buy it.

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