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Reef Tank Pests

As our nano reefs progress over time a few new corals, fish, cleanup crews, and liverock are typically added to our systems. But sometimes we get more than we bargained for - pests. Commonly called hitch hikers, most reef aquarium pests come along with livestock added to the tank. Other reef tank pests appear when there is an issue with water quality. Worms, algae, anemones, crabs, and shrimp are the most commonly seen aquarium pests.

Aptasia (Glass Anemones, Rock Anemones)
Aptasia anemones can pose a serious threat to your nano reef if left to spread. They sting or kill other corals around them, and reproduce rapidly. The sooner aptasia is removed the better your chances are of erradicating them. It is absolutely vital that these do not go unattended.
The most successful method of removing aptasia is by injecting them. Using a syringe, inject each anemone with a concentrated solution of kalkwasser [Calcium Hydroxide, Limewater]. However, if you have a large population of aptasia and your tank is under 10 gallons, this method may cause too much of a calcium change. The secondary solution is to use very hot - near boiling - water. If successful, the anemones will shrivel up and die within a day or two. If you do not have luck the first time, repeat the process until they go away. Be sure to move quickly or else the anemone will retract.
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Bubble Algae (Valonia)
Bubble algae are a fairly harmless reef tank pest in small quantities. It's not uncommon to see bubble algae in nano reefs with good water quality. It becomes a problem, however, when it spreads. It can grow over corals in the tank and snuff them out. Bubble algae are able to spread fast because each bubble releases algae spores when broken. It's seen either as one large bubble or a small cluster of little bubbles.

When removing bubble algae Be careful not to pop any bubbles. If the bubbles are large (about the size of a marble) you should be able to gently pull them from the rock. If possible, remove the rock the bubble is on and pull it off outside of the aquarium. If your bubble algae is a small cluster, concider adding an emerald crab [Minthrax] to the tank. They are nano reef safe and great for controlling bubble algae.

Mantis Shrimp (Stomatopods)
Mantis shrimp can enter into a nano reef when it is first setup, or new liverock is added. They come as hitch hikers within the rock, from both the Atlantic and Pacific. Not all batches of liverock will contain a mantis shrimp though. Mantis shrimp are predators, feeding on crustaceans and fish by smashing or spearing them. Signs that one is in you nano reef are: loud clicking sounds, missing fish, killed snails/crabs, or broken shells. They hide in small crevices within rocks or corals.
Removing a mantis shrimp is not a simple task. It would be wise to wear heavy gloves before handling a mantis shrimp. Most mantis shrimp that make it into aquariums are small, but larger ones have been known to break fingers. Fortunately nano reefs are not very large, so it should be easy to find. With this in mind, the following are methods that have been know to work:

  • If you know which rock the mantis is hiding in, remove it from the aquarium and place it in a bucket with water from your tank. If there is no life on the rock that needs to be preserved, place the rock in a bucket of carbonated water. If the rock has other life on it, you can use a turkey baster to squirt carbonated water [club soda] into the hole the shrimp is in. Either way the shrimp should evacuate the rock in time.
  • Buy or make a trap specifically for mantis shrimp. There are quite a few traps available at fish stores or online catalogs. DIY plans can also be found online. You may also want to research a trap before you buy it, to make sure it has been effective for others.
  • If the rock cannot be removed from the aquarium, the shrimp can be taken out with a net. This is, however, not easy. At night time, with the tank's lights off, simply wait and watch for the shrimp to come out and feed. Try using live bait to lure it out as well. If you can move quickly, it's possible to net it while it is away from its burrow.

Not every method will bring success for everyone. Remember that it takes patience to win the battle. If one method doesn't work out, try another.

  • albertthiel, escholl, Julian_blnc and 7 others like this


Wiz Khalifa
Jan 19 2013 06:49 AM

Thank you for posting this! I just got a 6 gallon fluval cube givin to me. The guy I got it from told me it was established and it is, there is live rock and live sand in it. With a few unknown snail(im going to look that up now) and a clown fish. But it had a stressful move it was a 2 hour car ride and the guy didnt move the rock or fish just wrapped up the tank and said I'd be good to go with fish and rock in it. But now some of the rock is purple, and there is dark red stringy like algae almost everywhere. Its gone down in the last few days but how do I remove it? Sorry for the story, thought my first post misewille be a long one! ;)

For Aptasia I have been successful in suffocating them. What I do is take some of my Coral Putty (which happens to be coralin algae color) and put a blob over the Aptasia. When i get close to it, it retracts which makes it not so bad in terms of how much putty you need. Then after a while I crack off the putty and the Aptasia is dead. I also use this technique for getting rid of Vermitid snails by 'filling' their tubes with the putty (does not require much)

    • Desmo996 likes this

Or, if it's a Mantis, you could just give it to me :)

You could also try getting peppermint shrimp (Lysmata Wurdemanni).  These are natural predators of the Aptasia and will eat them if not fed other food.  Make sure you ask for them by the scientific name as some other shrimp are also sold as peppermint shrimp.

Sep 23 2014 09:17 AM
How about flat worms? I am loaded in a nano 6
Dec 28 2015 05:23 PM


I just set up a 29 gallon BioCube.  I noticed this on the limerick today. What is it? I suspect that it is a type of nudibranch, but I don't really know for sure. What I really want to know is what it is and if it is safe to keep in my tank, or whether I should get it out somehow.

If you don't have sponges in your tank then you might have a problem becouse that's what they eat but if a nudibranch dies is possible that it can couse problems but don't worry it's not like a sea apple, but if it dies then try to get what's left of him out and place carbon bags or a reactor

I have just removed my first aiptasia in my first saltwater tank by filling a turkey baster with boiling water then squirting the pest with the water and then sucking it up as soon as it shrank and broke up.