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Clownfish and their Host Anemones
in the Aquarium

Ocelaris Clownfish (Amphiprion ocellaris) with Giant Carpet Anemone (
Stichodactyla gigantea)

By Tony Griffitts

Most aquarium hobbyists have always dreamt of having a successful aquarium with clownfish and host anemones.  Unfortunately many have had difficulty keeping the host anemones alive, or purchased an anemone their clownfish refused to accept as a host.  Another problem encountered for reef aquarist is the anemone moving around the tank stinging corals.  The purpose of this article is to remedy some of these problems for the aquarist and hopefully increase the survival rate in captivity of these magnificent animals.

While there are 10 species of host anemones and 30 species of clownfish, I will stick to the six most common host anemones, and eleven clownfish species the hobbyist is likely to encounter in the trade. 

All of the host anemones cannot be grouped into the same general care requirements.  Each species has its own requirements and these requirements need to be met in order to have a chance at keeping these animals happy and healthy.  There are a few aquarium requirements that are important to all the host anemones, low nitrate, good lighting system, good water movement, and food.

Nitrate (NO3) must be monitored when keeping these host anemones.  Probably the most common factor in the demise of host anemones in the aquarium is high nitrate level.  A nitrate level above 20 ppm is the number one common factor in unsuccessful attempts to keep these anemones.  I recommend that you try to keep nitrate below 15ppm.

Using a deep sand bed (3 inches [7.5 cm] of fine sand) has proven to be one way to help control the nitrate in the aquarium, and I highly recommend that you make the investment before attempting to keep these anemones.

A refugium with fast growing macro algae will help reduce and control nitrate accumulation in a aquarium system. It should be strongly considered when designing a system to house host anemones, as they are excellent at controlling nitrate. A bright lighting system over the refugium is a must.

Lighting is also an important factor.  Most lighting systems that come with aquariums are inadequate for keeping healthy host anemones.  Host anemones have algae (known as zooxanthellae) that live inside their tissue that provide a major food source for the animal.  You need moderately strong lighting to keep the algae healthy.  I recommend compact fluorescent lighting systems on aquariums 2 feet (60 cm) or less in depth.  Use 10000K or 6700K bulbs (or combination of both).  Don't waste a bulb socket on actinic (blue light) bulbs.

A moderate current also seems to be a factor in keeping these animals looking good.  The water movement should be strong enough so the current is gently swaying the animal's tentacles.  If you use power head pumps to create extra current in the aquarium, I recommend that you use a pre-filter like Hagen's Quick Filter attached to the intake so anemones that happen to be on the move do not get sucked up by the power head.

Host anemones are carnivores, while they are not likely to eat a healthy fish or invertebrates in the aquarium, they will eat sick or dying animals.  I recommend that they be fed 2 to 3 times a week.  Offer the anemones large krill, shrimp (jumbo shrimp), or fish.  I have seen a carpet anemone 6 inches across the disk eat a sick 4 inch (10 cm) tang, so they can eat large animals nearly their own size.  Place the food in the tentacles of the anemone.  Within a few seconds the anemone will often fold the disk around the food and the mouth will begin to swell.  When you first introduce an anemone to the aquarium do not be surprised if it will not eat for several weeks, this is common.  Once the anemone is comfortable with its new environment it will start to eat.

There are still some unknown factors in relation to host anemone health, even sometimes when all environmental factors look optimal some anemones still die.  If it does die in your aquarium remove it as soon as possible, as they can pollute your tank quickly.

Aquarium salinity should be kept between 1.024 and 1.026.  Temperature of 78° to 82° F (25° to 28° C) is ideal, but 72° to 86° (22° to 30° C) is acceptable, + or - 4° F (2° C) beyond that could be a problem.  Protein skimmers are not necessary for the health of the anemones.  Many healthy anemones have been maintained in aquariums that do not have protein skimmers.  Minimum recommended size of the aquarium is 25 gallons (95 l), but keep in mind that some of the host anemone species can get up to 3 feet (1 meter) across the disk.  Choose the appropriate species of anemone for the size of aquarium.

Anemones are not a threat to healthy fish and invertebrates, but they will eat sick, dieing, or dead fish and invertebrates.

You can keep more than one species of anemone in the aquarium.  I have witnessed in the sea four species of host anemones (Entacmaea quadricolor, Heteractis crispa, Heteractis magnifica, Stichodactyla mertensii) on one rock all in contact with each other and there appeared to be no signs of distress from the anemones possibly stinging each other.

The most common host anemones in the hobby are Entacmaea quadricolor (Bubble), Heteractis crispa (Sebae), Heteractis magnifica (Ritteri or Magnificent), Heteractis aurora (Beaded), Macrodactyla doreensis (Long Tentacle), Stichodactyla gigantea (Giant Carpet), and Stichodactyla haddoni (Haddon's Carpet).

Cinnamon Clownfish (Amphiprion  melanopus) with Bubble Anemone (Entacmaea quadricolor) Entacmaea quadricolor, the Bubble (some times called "Bulb") Anemone is by far the hardest host anemone you can buy.  It is found on reef areas with its foot attached to a crevice in the rock or coral.  The color of this anemone is highly variable, with the most common colors being a brown, green, or orange.  Less common specimens can have a colored tip on the tentacles that could be white, pink, or orange.  This anemone has long tentacles from 1 to 6 inches (2.5 to 15 cm) in length, often with a swelling near the tip of the tentacle, but not always.  The oral disc can be as much as 16 inches across, but 6 to 12 inches (15 to 30 cm) is more common.  The column color is also variable, but the most common is a light brown, less common is purple.  This anemone will often move around the tank until it finds a suitable place to hide its foot.  One technique to keep this anemone in place is to cut a 1-½ inch (3.75 cm) PVC pipe approximately 6 inches long.  Place the pipe vertically in the sand with at least 4 inches exposed.  Place the foot of the anemone in the hole.  The anemone will attach to the inside of the pipe.  After the anemone is attach for a few days you can wedge the pipe in between your rocks.  This anemone is very well known for its ability to multiply in the aquarium by fission (splitting in half).  The Rose Bubble (orange color bubble) is the most common variant know to multiply, but I have seen other color variants split.  This fission can take place very quickly, often over night.  Not all Bubble Anemones seem to have the gene that allows them to split.  I have kept some specimens for years and never had them divide.  In my experience in diving off of the island of Negros, Philippines I only encountered Tomato (Amphiprion frenatus) and Maroon (Premnas biaculeatus) Clownfish in this anemone, yet I was able to identify five other species (A. ocellaris, A. sandaracinos, A. perideraion, A. polymnus, A. clarkii) in the area in other host anemones.  This anemone is widely accepted as a host anemone by many species of clownfish. The Cinnamon (A. melanopus), Clark (A. clarkii), Tomato (A. frenatus), Fiji Barberi Tomato (A. barberi), and Maroon (Premnas biaculeatus) are the common clownfish species known to occupy of anemone in the sea.  The Bubble is an excellent choice for your first attempt at keeping host anemones.

Clarkii Clownfish with Sebae Anemone Heteractis aurora, the Beaded Anemone is sometimes available in the hobby.   This anemone can be found on a sandy bottom, often next to rocky reefs. The color of this anemone is normally a light gray.  Tentacle length can be as long as 2 inches (5 cm), and the oral disk can be as much as 12 inches (30 cm) across, but most commonly seen in the retail store at about 6 inches (15 cm) across.  This anemone will require a sandy substrate to hide its foot.  The Orange-fin Clownfish (A. chrysopterus), Clark (A. clarkii), and may other clowns of the clarkii complex are known to occupy this anemone in the sea.

Clarkii Clownfish with Sebae Anemone Heteractis crispa, the Sebae Anemone is by far the most common host anemone found in the hobby.   This anemone can be found on sandy bottoms, rocky reefs, and in the middle of large coral structures.  The color of this anemone is normally a light brown with pink tips on the tentacles.  These anemones often show up in retailer's tanks as white and sometimes yellow with pink tips.  These anemones have lost their zooxanthellae in transport.  Although I prefer to buy these anemones with the zooxanthellae in good shape, it is quite common for the zooxanthellae to grow back in time in a properly lit reef tank. Tentacles length can very from 1 to 4 inches, and the oral disk can be as much as 20 inches (50 cm) across, but most commonly seen in the retail store from 4 to 10 inches (10 to 25 cm) across.  This anemone will often move around the tank until it finds a suitable place to hide its foot. It is often confused with Heteractis malu.  The Cinnamon (A. melanopus), Clark (A. clarkii), Pink Skunk (A. perideraion), Orange Skunk (A. sandaracinos), Percula (A. percula), and Red Saddleback (A. ephippium) are the common clownfish species known to occupy this anemone in the sea.

Ocelaris Clownfish with Ritteri Anemone Heteractis magnifica, the Ritteri or Magnificent Anemone is one of the largest host anemones.  It is found on rocky reefs with its column exposed.  The color of the column is highly variable, but usually a light brown, purple, blue, orange, or maroon red.  The tentacles come to a blunt point and are usually end in white, green or yellow. The tentacle length is around 1 to 2 inches (2.5 to 5 cm), and the oral disk can be as much as 3 feet (1 meter) across, but usually in the hobby specimens are 8 to 12 inches (20 to 30 cm).  In the aquarium, place this anemone on a large rock that is the high point in a rock structure.  Keep the rock at least 2 to 3 inches (5 to 7.5cm) away from the aquarium walls and other rocks to keep it from migrating.  Since this species gets very large, it is recommended that you place this anemone in aquariums that are at least 18 inches (45 cm) wide.  The Cinnamon (A. melanopus), Clark (A. clarkii), Pink Skunk (A. perideraion), Percula (A. percula), Ocellaris/False Percula or Nemo (A. ocellaris), and Skunk (A. akallopisos) are the common clownfish species known to occupy this anemone in the sea.

Long Tentacle Anemone Macrodactyla doreensis, the Long Tentacle Anemone is one of the easier host anemones to keep.  It is only found on sandy bottoms and is not normally much of a problem in reef tanks as long as it can bury its foot in the sand.  The color on this species is variable, most often brown, brown with a green cast, or striped, and rare specimens can be purple.  Tentacles are not as numerous as other host anemones and can be over 6 inches (15 cm) long.  The oral disk is usually 8 to 10 inches (20 to 25cm) wide on imported specimens, but can be as much as 18 inches (45 cm). The column is often red, but can also be a light brown or orange. The Clark (A. clarkii), Pink Skunk (A. perideraion), and Saddleback (A. polymnus) are the common clownfish species known to occupy this anemone in the sea.  I have seen this anemone accepted as a host by many other clownfish (A. ocellaris, A. frenatus, A. melanopus) in the aquarium when the preferred host is not provided.

Giant Carpet Stichodactyla gigantea, the Giant Carpet is not the largest carpet anemone, but is usually the largest carpet we see in the hobby.  Stichodactyla mertensii (Merten's Carpet) is the largest carpet that is very similar in appearance to S. gigantea, but it is found on rocks.  S. gigantea is normally found on sand often at the base of where the rocks meet the sand.  Color of this anemone is variable, but most often a light brown, or gray, and rare specimens from Papua New Guinea being purple.  The tentacles are numerous and only about a ½ inch (1.25 cm) long.  The oral disk can be as much as 18 inches (45 cm) across, but imported specimens are normally 8 to 12 inches (20 to 30cm).  The oral disk has irregular folds, while S. mertensii is more flat, and S. haddoni has regular folds.  The tentacles are very sticky and can pull off when touched.  It is best to ware rubber gloves when handling carpet anemones, as the do not seem to stick to rubber.  This is one of the more difficult anemones to maintain in the aquarium.  The Clark (A. clarkii), Pink Skunk (A. perideraion), Percula (A. percula), and Ocellaris/False Percula or Nemo (A. ocellaris) are the common clownfish species known to occupy this anemone in the sea.

Saddleback with Haddoni Anemone Stichodactyla haddoni, Haddon's Carpet is the smallest carpet anemone.  It is always found on the sand.  Color of this anemone is variable, but often light brown, green, gray, and variegated with white streaking across the disk.  The tentacles are short and compact.  The oral disk often has regular folds and in most specimens less than 10 inches (25 cm) across, but can be as much as 12 inches (30 cm).  This is the most common carpet in the hobby and probably the easiest to keep.  The Clark (A. clarkii), and Saddleback (A. polymnus) are the common clownfish species known to occupy this anemone in the sea.

Clownfish are a member of the damselfish family that evolved a unique symbiotic relationship with some species of sea anemones.  These fish appear to have evolved a resistance to the stinging cells of their host.  Clownfish are also long lived small fish that have been known to live 20 plus years.

Tomato Clownfish in Flower Pot Coral

This Tomato Clownfish has adopted a Flower Pot Coral as a host.

Not all the 29 species of clownfish will go in all 10 species of host anemones.  In fact, only one species of clownfish, the Clark's Clownfish (Amphiprion clarkii) is know to occupy all 10 species of host anemones in the sea.  Most clownfish are very selective about which anemone they will accept as a host in the sea, but in the aquarium, in absents of a preferred host they will often accept a host anemone they are not normally associated.  In some cases, clownfish will use large polyp stony corals, and some times soft corals as a host when a host anemone is not provided.  As a general rule, it is best to pair the clownfish with a host anemone they are associated with in the sea, as they will not always accept other host anemones.

All Clownfish start out as males, and in the absent of a female the dominant male will in time change to a female.  The female is normally the larger fish of a mated pair.  In some species of clownfish the female is also darker in color.  If you try to pair clownfish I recommend that you buy one larger and one smaller clownfish.  The smaller clownfish (normally the male) will shake whenever the larger clownfish shows aggression towards it, this will often trigger the larger fish to back off.

In the aquarium it is best not to try to mix the different species of clownfish in the same aquarium, unless the aquarium is very large and has different species of host anemones.  As a general rule never try to mix the Maroon Clownfish (Premnas biaculeatus) with any other clownfish in the aquarium, as the results are usually not very good for the other clownfish.  In the sea, on a rare occasion I have seen Clark's Clownfish sharing an anemone with other clownfish species (A. polymnus), but this is not the norm.  It is not unusual for clownfish to try to feed their host with a large piece of shrimp or fish.  Clownfish will often spawn in captivity as long as the water quality is good and a pair has been kept together for several months.  Pre-spawning behavior will consist of the pair biting at a spawning site to try to clean a surface where they intend to lay their eggs.  Clownfish normally lay their eggs close to an anemone on a hard surface.  Once they spawn they will spawn again on a regular basis, usually at least twice a month.  Depending on the species of clownfish the eggs can range from pink in color to red.  The eggs are large as in comparison to most other marine fish kept in the hobby, about 2 mm long and 1 mm wide.  As the eggs age you will notice the eyes develop on the embryos.  The eggs normally hatch at dusk.

Skunk Clownfish Amphiprion akallopisos (Skunk) usually come into the hobby from Indonesia, but can be found as far West as East Africa.  This clownfish is very similar to the Orange Skunk (A. sandaracinos) in appearance.  The Skunk is orange on the belly area, but as you get to back of the fish the orange fades to a pink.  The white stripe down the back ends in a point above the top lip.  It is associated with the Ritteri (H. magnifica), and Merten's Carpet (S. mertensii) in the sea.

Clarkii Clownfish Amphiprion clarkii (Clark's) is one of the most common clownfish in the hobby.  It is found from Micronesia to the Persian Gulf and from Northern Australia to Southern Japan.  The color of this clownfish is variable, but normally it has three white stripes, one behind the eye, one mid body, and one at the base of the tail.  The body color can be mostly yellow, orange, or black.   In the sea it is not unusual to see large adults of this clownfish venture 20 or 30 feet (7 to 10 meters) away from its host, often vocalizing and displaying to other Clarks from other host anemones, most other clownfish stay close to their host.  This is the only clownfish that can be found with all 10 host anemones including the Adhesive Anemone (Cryptodendrum adhaesivum).  It is a great choice for an aquarium if you want a clownfish anemone relationship.  

Red Saddleback Amphiprion ephippium (Red Saddleback) come into the hobby mostly from Indonesia and western Thailand.  This clownfish looks very similar to the Tomato and Cinnamon clownfish in body shape, but it lacks the single white stripe behind the eye in the adults.  A white stripe may appear in juveniles and a very small white stripe in sub-adults.  This clownfish is normally associated with the Bubble (Entacmaea quadricolor) and Sebae (Heteractis crispa) anemones in the sea.

Tomato Clownfish Amphiprion frenatus (Tomato) mostly come into the hobby from the Philippines, but are found from southern Japan to Indonesia.  This is one of the most common clownfish in the hobby.  Usually bright red as juveniles, older females will often be mostly dark red or black on the body.  Juveniles can often be seen with 2 or 3 white stripes, but it will only have one stripe behind the eye as an adult.  The preferred host for the Tomato is the Bubble Anemone (Entacmaea quadricolor), but I have seen it accept Sebae (Heteractis crispa) and Long Tentacle (Macrodactyla doreensis) anemones in the Aquarium.

Cinnamon Clownfish Amphiprion melanopus (Cinnamon) found from southern Philippines, Great Barrier Reef (Australia), to Polynesia.  This is one of the species of clownfish that looks very similar to the Tomato (Amphiprion frenatus).  The Cinnamon normally has a red face and dorsal fin and a predominantly black body, pelvic and anal fins, and a pail yellow tail.  Most have a white stripe behind the eye, but in some fish in some populations the white stripe can be absent.  The Cinnamon is found in the Bubble (Entacmaea quadricolor), Ritteri (Heteractis magnifica), and Sebae (Heteractis crispa) anemones in the sea.  At Aquaworld we have a mated pair of Cinnamon clownfish that occupy a Long Tentacle anemone (Macrodactyla doreensis).

Ocelaris Clownfish Amphiprion ocellaris (Ocellaris/False Percula or Nemo) is the most common clownfish in the hobby.  It is found from Northwest Australia to the Ryukyu Islands of southern Japan.  Most of the imports come from Indonesia and the Philippines.  This fish is nearly identical to the Percula clownfish (Amphiprion percula) in appearance.  The general differences between the two species is the thicker black border surrounding the white stripes on the Percula, and the amount of dorsal spines, Ocellaris having normally 11 and Percula having normally 10.  The thickness of the black border can vary on Ocellaris, on some fish it is very thin while on others it can be a couple millimeters wide.   The color of Ocellaris is variable, from light yellow, orange, brown, and in rare specimens black (reported to come from Darwin, Australia).  The black color variant starts out as brown as a small juvenile and turns black while a sub-adult.  This species is commonly captive bred in the U.S.A. and the U.K.  Unfortunately this clownfish can often be difficult to pair with an anemone they are not normally associated with in the sea.  The anemones they are normally associated with are Ritteri (Heteractis magnifica), Giant Carpet (Stichodactyla gigantea), and Merten's Carpet (Stichodactyla mertensii), all these anemones get very large so it is recommended that if you would like to keep one of these anemones you should have a 120 gallon aquarium or larger.  An alternative anemone to pair with this clownfish with is Haddon's Carpet (Stichodactyla haddoni), this is a smaller anemone and the Ocellaris clownfish will often accept it within a few days after being introduced. 

Percula Clownfish Amphiprion percula (Percula) is not very common in the hobby, but does occasionally show up in imports from Indonesia.  This fish is found from Great Barrier Reef (Northern Queensland, Australia), the North side and Southeast tip of New Guinea and as far East as Vanuatu.  The "True" Percula clownfish normally costs 2 to 3 times as much as the common color form of the Ocellaris clownfish.  The color on this fish is variable from light orange to red, and often with such thick black borders around the white bands that they often connect the white bands.  The anemones true Percula clownfish are normally associated with in the sea are the Sebae (Heteractis crispa), Ritteri (Heteractis magnifica), and Giant Carpet (Stichodactyla gigantea).

Pink Skunk Clownfish Amphiprion perideraion (Pink Skunk) is a commonly available clownfish, but I find it not to be very popular with most hobbyists.  They normally come in from the Philippines and Indonesia.  They are found from western Indonesia and northwestern Australia to southern Japan, and as far East as Micronesia.  This fish is normally a pink color with a white stripe down the back and a white stripe down the operculum (gill plate).  The anemones the Pink Skunk is normally associated with in the sea are the Sebae (Heteractis crispa), Ritteri (Heteractis magnifica), Long Tentacle (Macrodactyla doreensis), and Giant Carpet (Stichodactyla gigantea).

Saddleback Clownfish Amphiprion polymnus (Saddleback) is found from northern Australia to southern Japan, and from western Indonesia to the Solomon Islands.  It is imported from Indonesia and the Philippines.  The color on this fish is variable, light brown, black, and orange and black.  This clownfish has 2 or 3 broad white bands with the middle band starting mid body and extending into the to back of the dorsal fin.  The middle stripe often resembles a horse saddle.  The black color form of this clownfish is often misidentified as a Black Percula, of which is also a misidentification of the Black Ocellaris.  The anemones the Saddleback is normally associated with in the sea are the Sebae (Heteractis crispa), Long Tentacle (Macrodactyla doreensis), and Haddon's Carpet (Stichodactyla haddoni).

Orange Skunk Clownfish Amphiprion sandaracinos (Orange Skunk) is found from southern Japan to northwestern Australia to the Solomon Islands.  It is imported from Indonesia and the Philippines.  It is occasionally seen for sale, and is one of my favorite clownfish.  This fish is very similar to the Skunk Clownfish in color, except that the overall color of the fish is orange, and the white stripe down the back extends all the way to the top of the upper lip.  The anemones the Orange Skunk is normally associated with in the sea are the Sebae (Heteractis crispa), and Merten's Carpet (Stichodactyla mertensii).   

Maroon Clownfish Tending Eggs Premnas biaculeatus (Maroon) is the only clownfish of the genus Premnas.  This is the largest clownfish with females some times reaching as much as 7 inches (16.25 cm).  Maroon Clownfish can be found from the Philippines to western Thailand and Indonesia, Northern Queensland (Australia), to Vanuatu.  Females of this species are usually a dark maroon red or brown in color while the males are more bright red.  This clownfish most often has 3 white or yellow bands.  The yellow band is reported to come from Sumatra (D. G. Fautin/G. R. Allen, 1992), but I have also seen them in the Philippines.  The yellow band Maroons always demand a higher price than the white band.  It is often difficult to pair this clownfish.  Large females will some times if not often kill a potential mate when introduced to an aquarium together.  If you try this you should keep an eye on the fish for at least an hour to make sure the pair will get along.  It is best not to try to keep this clownfish with any other clownfish, as they can be very aggressive towards other clownfish species.  In the sea, the Maroon Clownfish is only associated with the Bubble Anemone (Entacmaea quadricolor).  An alternative anemone that Maroon Clownfish will sometimes accept is the Long Tentacle (Macrodactyla doreensis).

While clownfish can be kept successfully in the aquarium without a host anemone, they do seem to enjoy life in an aquarium a lot more when they have a host.  Remember though that if you want to keep a host anemone you will need to set up the aquarium with the proper lighting and filtration.  Host anemones are one of the more difficult animals to keep in a reef aquarium, but paired with clownfish they can also be one of the most entertaining.

If you would like more information on clownfish and host anemones I recommend the book "Anemone Fishes and their Host Sea Anemones", by Daphne G. Fautin and Gerald R. Allen, Published by Western Australian Museum 1992, Rev. ed. 1997, ISBN 0 7309 8392-7, and "Anemonefishes, Their Classification and Biology", by Dr. Gerald R. Allen, Published by T.F.H. 1972, ISBN 0-87666-001-4.

Published - 20050821



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