Common Name: Glassrose Anemones
Aiptasia spp. anemones are probably one of the most bothersome pests in the reef aquarium. In some cases they can proliferate so quickly that they can completely cover an entire aquarium in only a few months. In aquariums that receive regular feedings, they can multiply even faster. Some aquarists consider this is a desirable thing and they proudly present these aquariums as "reef tanks'1,
Aiptasia anemones stinging a colony of star polyps, Pachyclavularia sp. S.W. Michael.
however, we do not share the same view. We have even seen dead coral rocks covered with Aiptasia offered for sale as "anemone rock". Do NOT buy such rocks! These small anemones can easily sting and irritate corals and clams to death and should not be allowed to gain a foothold in the aquarium. Aiptasia are usually introduced along with live rock when setting up a new aquarium. They can also arrive on pieces of rock with corals on them, or with zoanthid and mushroom anemone colonies.
Removal: There are several techniques that can be employed to eliminate these pests from the aquarium but they can be divided into twro basic categories: biological and mechanical. Biological controls consist of using natural predators to eliminate the anemones. One drawback to this method is that these organisms
may eat not only the Aiptasia but also any other cnidarians in the aquarium such as zoanthids. For this reason, it is prudent to introduce these predators to a newly established aquarium before adding any other corals. This will cause them to search the live rock and eat any Aiptasia they find. Once all the Aiptasia have been eaten, the predators can be removed and corals introduced.
Several species of butterflyfish have been used in this manner with varying degrees of success. The best species for this purpose is the Raccoon Butterflyfish, Cbaetodon lunula (M. Awai in Sprung, 1990). Klein's Butterfly, Chaetodon kleinii, will also eat Aiptasia (Fossa and Nilsen, 1993c), as will the Caribbean Banded Butterfly, Chaetodon striatus. Be warned, however, that these fish may eat almost any coral or anemone. The Copperband Butterflyfish,
Chelmon rostratus, has been used with varying degrees of success and has the added benefit of not bothering other corals, although they will eat annelids such as feather duster worms. Certain shrimp can also be used to control Aiptasia but they will also eat other corals like zoanthids. Some have suggested using the Peppermint shrimp, Rhynchocinetes uritai (Tullock, 1991). These shrimp will, however, also eat zoanthids such as Yellow Polyp, Parazoanthus gracilis. Furthermore, these shrimp tend to eat only juvenile Aiptasia, leaving behind the reproductive adults. Certain species of anemone-eating nudibranch such as those belonging to the genus Spurilla (e.g. the Caribbean nudibranch, Spurilla neapolitana) can also be used successfully in newly set-up aquariums that contain no other corals or anemones. It is also possible that the Caribbean nudibranch Dondice occidental is will eat Aiptasia, and it may not bother other anemones or corals.
The Copperbanded Butterfly, Chelmon rostratus, will eat Aiptasia anemones. J.C. Delbeek.
Mechanical removal can be used at any time before or after other animals have been added to the aquarium but may involve the removal of the rock the anemones are attached to. One of the dangers in mechanical removal is that Aiptasia have amazing regenerative powers. If even a small portion of tissue is left behind, it can regrow into a new individual. If the tissue becomes lacerated into several small pieces, each piece has the potential to develop into a new anemone. Therefore it is important that all tissue be removed. Mechanical removal can be quite difficult and time consuming since most Aiptasia are anchored in holes and crevices in the rock. Even when lightly touched they can retract into these holes with amazing speed!
One method of mechanical removal involves placing the rock with the anemones into a separate bucket. Then, using a knitting needle (or equivalent), simply grind the anemone out of the hole. Scrape as forcefully as you can to remove all the tissue. A strong stream of saltwater can then be used to rinse out any loose tissue. It is also possible to fill the hole with freshwater, to destroy any remaining tissue. This will kill any other marine organisms in the hole too, but the loss is usually minimal. Some authors have recommended j removing the rock into boiling water and then scrubbing it clean (Haywood and Wells, 1989). This technique should only be used on dead rock and NEVER on live rock or rock covered with coralline algae!
Another method involves the use of an hypodennic needle and various solutions. The needle is used to inject a solution into the body of the anemone, killing it quickly. When injecting the anemone, the needle must pierce the body wall without passing completely through the anemone. The solution must be injected so that it fills the body cavity. One of the problems involved with this method is that the anemones must be easily accessible, and let's face it, they don't just sit there and take it, they rapidly retreat into the rock . Another problem is that some of these solutions can be detrimental to other tank inhabitants so only a few anemones can be treated each day. A supersaturated solution of calcium hydroxide (2 grams in 100 millilitres) has been used in this manner with excellent results without any noticeable side affects to the rest of the aquarium (see Hemdal, 1992). Approximately 1-2 mL is drawn into a 5 mL syringe with a wide-bore needle. The solution should be kept agitated to prevent clogging of the needle by gently twirling the syringe between the fingers. A 5% solution of hydrochloric acid injected by syringe has been recommended also (Wilkens and Birkholz, 1986) as has boiling water (P. Wilkens, pers. comm.). The boiling water can be effective even without penetrating the anemone, but be careful not to burn yourself!
Aquarists have also successfully killed these anemones by injecting them with a small amount of dilute copper sulfate solution, or by inserting a copper wire into them and leaving it there for several minutes. We caution that while copper is an important trace element for invertebrates, excess copper is highly toxic to them. Therefore wre do not encourage the novice to use copper to control Aiptasia, though it can be done safely by the experienced aquarist.
Common Names: Flatworms, Planaria
Flatworms come in many shapes and sizes. Some are parasites, commensals or opportunistic feeders of corals while others are predators and scavengers feeding mainly on algae, detritus, dead organisms, copepods or diatoms. These small wrorms are dorso-ventrally flattened and normally have a rounded head with a forked tail. In the aquarium, the non-parasitic forms are commonly encountered in the first few months when a reef aquarium with live rock is setup. The parasitic, opportunistic and commensal forms are primarily introduced with new coral specimens.
Many species of flatworms can reproduce both sexually and asexually and for this reason all it takes is one specimen to infect an aquarium. Their regenerative powers are phenomenal. If a single individual is cut into several pieces, each piece can develop into a new adult.
Flatworms have a variety of feeding mechanisms. Some species envelop and trap prey using their skin folds and a sticky slime. Others pierce the body wall of their prey using their protrusible pharynx and proteolytic enzymes, and suck out the contents (Barnes, 1974).
There are approximately 14 different non-parasitic forms that have been seen in aquariums (Beul, 1987). Some of these feed on small copepods, others feed on diatoms and others act as scavengers (Wilkens and Birkholz, 1986; Beul, 1987). The most commonly encountered flatwonn in the reef aquarium are the small, semi-transparent, whitish ones belonging to the suborder Maricola. These are usually found in newly setup aquariums with live rock. They have a length of 5-10 mm (0.25 in.) with a rounded anterior end and fork-shaped rear end. Mainly active at night, they are usually found crawling along the glass or rock but they can swim short distances when disturbed. These small worms should not cause any undue alarm as they are actually quite helpful and will usually disappear within a few months as their food supply diminishes. If they do not, it could be that you are overfeeding the aquarium (Wilkens and Birkholz, 1986). Colourful, iridescent flatworms that feed on diatoms and other microalgae sometimes proliferate in aquariums with strong illumination and heavy growth of algae on the glass.
Reduction of the algae growth through limitation of plant nutrients usually causes the flatworm population to decline.
Another non-parasitic form (Convolutriloba retrogemmd) is rust-brown in colour and is an opportunistic feeder on photosynthetic corals (Wilkens and Birkholz, 1986; Lange and Kaiser, 1991). They grow to a length of 5 mm (0.25 in.) with two, and sometimes three, pointed projections on the rear (Beul. 1987). It is believed that these flatworms are not true parasites and only attack damaged or infected corals (Wilkens and Birkholz, 1986). They feed on the damaged tissues and ingest the zooxanthellae. Their colour comes from the fact they incorporate the zooxanthellae in their body wall and use them much as the coral did. For this reason they can multiply asexually very quickly in brightly lit aquaria and can quickly overrun an entire aquarium. These flatworms are usually found in aquariums that have Indonesian live rock, or they can be acquired by purchasing specimens from a dealer whose tanks see a high turnover of specimens imported from Indonesia.
Parasitic flatworms are usually distinguished by the fact that they are always found on their hosts. They are generally light grey to brown in colour and many species have a stripe down the back. Although many types of corals can be affected, mushroom anemones (Discosoma sp., Actinodiscus sp.) are the most often infected. Large polyped hard corals can also be infected, especially Elegance Coral (Catalaphyllia jardinei) and Bubble coral (Plerogyra sinuosa). Soft corals that can be infested include Sinularia, Cladiella, Li top by ton and Sa rc op by to n (Wilkens, 1990).
A plague of red planaria, Convolutriloba retrogemma. J.C. Delbeek,
Planaria infesting a specimen of Sinularia dura. Note that the stripes on the planarians look like the mouths of the zoanthid anemones on the right. J. Sprung.
Mushroom anemones infested with planaria. J.C. Delbeek.
Planaria can also affect stony corals such as this Turbinaria peltata. J.C. Delbeek.
Flatworms infesting a Dendronephthya soft coral in New Guinea. S.W. Michael.
Planaria can affect soft corals such as this Sarcophyton. L.N. Dekker.
If these flatworms are allowed to multiply they can completely cover the coral, resulting in its death. However, it is unclear if the coral dies from the flatworms or from lack of light. In some cases, the coral does not appear to be harmed by the infestation. It may be that the flatworms are merely feeding on the detritus and bacteria trapped in the body slime of the coral and not on the actual tissue (Wilkens, 1990). If this is true, then these species are commensals and not true parasites.
Removal: There are a number of methods that can be used to remove harmful flatworms from the aquarium. The best method is of course prevention. Check any purchases very closely for any sign of flatworms and remove them before placing the specimen in the aquarium. If possible, isolate the coral in a separate aquarium for a few days where you can closely observe it. Since the worms are quickly killed by freshwater, a brief (5-10 second) freshwater dip can be employed to prevent their introduction into the aquarium. In freshwater the worms immediately lose their grip and fall off (see additional information below).
No matter how careful an aquarist is, flatworms can still be introduced unnoticed. It is important to remove them as quickly as possible before they multiply. Failure to do so can result in a serious plague that will prove to be extremely difficult to control later.
Physical removal is possible when only a few corals are affected. For example, mushroom anemone colonies can be removed from the tank and vigorously shaken in a separate bucket of seawater. This will remove the majority of flatworms. Any remaining worms
can then be brushed off with a soft paintbrush and siphoned out (Wilkens, 1990).
Some species (e.g. C. retrogemmd) are attracted to light and this can be used to remove them from the aquarium. Turn off all the aquarium lights and shine a single light onto a spot in the aquarium. The flatworms will soon begin to collect at this point. It is now a simple matter of siphoning the flatworms from this area with a small hose (Wilkens, 1990).
If only a certain coral is affected it is possible to remove the coral and give it a short (5-10 second) freshwater dip (Wilkens and Birkholz, 1986; Beul, 1987; Ruiter, 1987a). This will effectively dislodge the flatworms from the coral. Make sure the freshwater is at the same temperature and pH as the aquarium, to avoid chemically shocking the coral. Not all corals will accept a freshwater dip. Such dips work best on mushroom anemones and stony corals, and the tougher soft corals Lobophytum, Sarcophyton and Sinularia.
Water chemistry changes can also be used to control flatworms. It has been found that increasing the specific gravity above 1.022 can rid a tank of flatworms (Wilkens and Birkholz, 1986; Ruiter, 1987a; Wilkens, 1990). However, mushroom anemones do not react well to such a change (Ruiter, 1987a). High pH values (8.4-8.6) can also reduce flatworm populations (Wilkens and Birkholz, 1986).
Natural predators of flatworms must exist or else they would multiply unchecked in the wild. The problem is that very few aquarists have found effective predators, and not every individual of a species will eat flatworms. For example, certain wrasse species are reported to eat flatworms. These include the Six-Lined Wrasse (Pseudocheil in us bexataenia) and the Yellow Wrasse (.Halicboeres chrysus) (Wilkens, 1990). A Leopard Wrasse, Macropharyngodon varialvus has been reported to eat flatworms on mushroom anemones and Sarcophyton soft corals, and it is possible that other members of this genus may do so too (DeVries, 1987; B. Carlson, pers. comm.). Wrasses of the genus Anampses may also feed on flatworms, and might be worth trying (B. Carlson, pers. comm.). The Spotted Mandarin, Syncbiropus ocellatus, has been recommended by Wilkens (1990) but it is not always effective. We have seen evidence that the Goldenheaded Sleeper goby, V. strigatus may eat the rust-coloured flatworm, C. retrogemma. Other bottom sifting gobies have also been observed eating them (Joe Yaiullo, pers.
Macropharyngodon wrasses may be planaria eaters. S.W. Michael.
Anampses wrasses may also be planaria eaters. S.W. Michael.
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Dragonettes such as Synchiropus picturatus, the psychedelic mandarin shown above, sometimes feed on planaria. J. Sprung.
comm.). Starfish from the genus Narcloa and snails of the genus • 7bais have also been found to feed on planaria, but only when the population of flatworms has not increased greatly (Wilkens, 1990).
Lange and Kaiser (1991) found that Tetra's Marin-Oomed™ was useful in eliminating the rust-coloured flatworms, C. retrogemma, from an aquarium that contained only leather corals of the genus Sarcopbyton. When used as directed the flatworms burst, releasing a red-coloured toxin into the water. This toxin is deadly to fish and must be removed immediately either by water changes or the use of large quantities of activated carbon. We recommend that this technique be attempted on aquariums that contain only Sarcopbyton, and only after all other methods have been exhausted. Other, safer, chemical methods for the removal of
flatworms will no doubt appear within the next few years.
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