By Bob Goemans
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Bob Goemans corresponds with Diane (New Brunswick, Canada)

Diane (New Brunswick, Canada) writes...

Dear Bob,

I have an algae problem. I've had this 30-gallon saltwater tank for about three years now and just can't seem to rid myself of a particular form of algae. I've looked up your website algae page but can't find this one.

The only pet store we have in this small town has told me to inject them with hot water, which I do on a regular basis but they come back very fast. I have a 405 Fluval canister filter system and UV steriliser but have just read that I should also have a protein skimmer so I will purchase that this afternoon, meanwhile, I was hoping you might know what the heck I can do with this problem.

In this tank I have a blue hippo tang, a yellow tang, two clownfish, a mandarin dragonet (which they never bothered to tell me didn't eat flake food but thankfully I have tons of copepods for him!) and I have a cleaner shrimp and another red shrimp they told me would eat this stuff but he doesn't even touch it. Another thing that I don't know if it's a problem or not is I have quite a few bristleworms. I have been plucking them out nightly but there are probably dozens in there yet!

Thanks so much if you help.


Diane in Pokeshaw, New Brunswick, Canada

Bob replies...

Hi Diane,

Thanks for your email and photos showing what was thought to be an algae problem. Actually, it's not an algae, but an Aiptasia anemone infestation, in fact, the worst I've ever seen! There must a 300 or more covering most things in your small aquarium! And I find it disturbing that a local fish shop is unable to properly identify these common pests or prescribe the proper ways to reduce or eliminate them.

These small brown anemones, who's sting can damage most corals, multiply quickly and must be removed or extinguished as soon as they show up in aquariums. Go again to my website ( and open the 'Animal Library' page. Then open 'Soft Corals' and look down its listing and find 'Sea Anemones.' Open that and go to Family Aiptasiidae and read the various ways to solve your problem. Nevertheless, because of the number of these pests in your aquarium (really an amazing amount!), would first remove whatever rock is easy to get at, then scrub it 'clean' with a stiff brush, maybe a denture toothbrush, wash it off under a stream of freshwater, possibly from an outside garden hose, then place it back in the aquarium. Be sure to wash it thoroughly as small body parts remaining will grow a new anemone. Do one rock, than another the following week, etc., until all that is reachable is cleaned. Meanwhile, and as soon as possible, recommend getting 6 - 10 'peppermint' shrimp (Lysmata wurdemanni - see their photo on my website), as they dine on these pest anemones. Stay after those that can be easily removed by removing what its attached to rocks and cleaning them off. These shrimp will take care of the rest of them, as they have in some of my past aquariums.

As for bristleworms, those under a couple of inches should not be a concern. Those larger may have to be removed. They usually multiply because the system is overfed, as they are great consumers of the uneaten foods. Again, if not overly large or too numerous, I would not be concerned at this time.

Wishing you the best with this project.


FYI the below is what is posted on my website and I make a point here to repeat it, as you'll see why when you read further.

Genus Aiptasia

These small brown rock/glass anemones are considered here only because they usually become pest-like in aquaria. Their sting can cause most corals to close-up and remain closed, and unfortunately they multiply quickly.

There are a few species of interest, e.g., A. pallida, A. pulchella, and A. diaphana, however, they all look alike to the layperson. They come from a wide range of localities and withstand a wide range of temperatures. Bottom line, it's the 'how to rid the aquarium of them' that is more important than 'how to maintain them!'

There are various ways to reduce and keep the population to a minimum, but there is no sure fire cure to rid the entire aquarium of this pest once it has gotten a foothold. If the hobbyist has a fish-only aquarium, they could introduce a Raccoon Butterflyfish (Chaetodon lunula), Klein's (C. kleinii), the Saddleback (C. ephippium), Tinker's (C. tinkeri), the Threadfin (C. auriga), or the Copperband (C. striatus ) which will eat these pests. Yet, should there be corals, feather dusters, star polyps or zoanthids in the aquarium, these fish will probably feast on them also.

Injecting it with boiling water or very hot Limewater causes it to turn a grayish color, effectively killing the entire specimen. Yet, sticking a needle into the anemone before it can withdraw is almost impossible. Locating a hypodermic syringe filled with hot Limewater about a quarter inch away from the anemone and shooting a stream of hot Limewater upon the anemone stuns the anemone and seems to prevent it from withdrawing/shrinking in size. It is then fairly easy to get the point of the needle into the still erect body and injecting it, effectively killing the specimen.

Another idea is using the sting from an Elegance coral (Catalaphyllia jardinei) to kill the anemone. This does work, as I have tried it!

Another way to destroy these pest anemones was brought to my attention by a fellow hobbyist in New York. He notes that a slush mixture of sea salt deposited directly on the anemone will cause it to immediately die. Simply take some aquarium sea salt and make a slush-like mixture and flow it directly on the anemone. A syringe is a good way of applying this mixture. It can also be flowed into cracks getting it down to where these pests may have a foothold.

The Nudibranch Berghia verrucicornis, native to the Caribbean and western Atlantic, only feeds on Aiptasia anemones. Juveniles measure about 1 cm, with adults reaching 3 cm within a couple of weeks. They are nocturnal. Unfortunately, once these pest anemones are eliminated, the nudibranch will die because of a lack of food supply. Of course, you could pass it along to a fellow hobbyist who has some of these pest anemones. This way, the nudibranch may still be available should they return to your aquarium in the future. Also, other nudibranchs that may be effective are Spurilla neopolitana and Baeolidia nodosa, however, their availability is questionable.

A recent biological control is thought to be the Red-legged hermit crab, Dardanus megistos. This small hermit appears to be safe in reef aquarium and is thought to dine on this pest anemone. Yet more than an occasional positive feedback is still needed to confirm its usefulness.

Another biological control is through the use of Lysmata wurdemanni, usually called the Peppermint Shrimp. This 2.5 inch (6 cm) shrimp has lengthwise lines of red covering a somewhat transparent body. It does not have claws like the Banded Coral Shrimp, however is an effective killer of Aiptasia anemones. However, they appear to also consume Yellow polyp anemones.

Scats (Scatophagidae), which are a brackish and/or freshwater fish, are also a very good consumer of Aiptasia anemones. They not only take a wide variety of foodstuffs, including copious amounts of vegetable matter, they also like these rock anemones.

Another possible solution is the use of a little known Filefish, Acreichthys tomentosus. It is said to reef safe, yet most filefishes are far from reef safe. Caution is advised.

Novel approaches such as the use of peppery hot sauce is not recommended, nor are chemicals such as hydrogen peroxide, hydrochloride acid or copper compounds. However, there has recently (late 2003) been another entry into controlling these pests with a foodstuff that is sprinkled over the anemone and after consuming this material, the anemone melts away. Said to be harmless to other invertebrate and works quite well in reef aquariums. Contact for more information.

Follow-up letter

Diane (New Brunswick, Canada) writes...

Hi Bob,

Oh, what a difference already. I got two more peppermint shrimp and then took some lemon juice concentrate and went after some of the remaining. I had to buffer my pH after that, as I know the lemon is acidic, but it worked wonders. I now have about 10% left of what I had originally. Funny when you said it was the worse you had ever seen cause I didn't send photos of the whole tank, - you would have been stunned for sure! I went to the pet store, email in tow and showed them. They actually were very interested in what it was and I gave them your website, maybe they'll learn something. In a small town it's hard when you only have one local pet store, which is why I always try to research what I'm looking for first, but the Aiptasia wasn't on my list, it just kind of crept up on me. Thanks so much for the information and just love your website. As for the bristleworms, I'm sure I was overfeeding so will try not to feed as much.

Thanks again.


Bob replies...

Hi Diana,

I'm happy to see my response helped. However, I did not mean 'lemon juice' when I said 'Limewater.' That term is commonly used to describe Kalkwasser, which is an additive used to bolster calcium and alkalinity. Put the word 'Kalkwasser' into your web's search engine for a full explanation.

As for bristleworms, very large ones, as explained can damage/feed upon corals. But smaller ones are more scavengers of uneaten foods/dead animals.





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