If you are an expert saltwater aquarium hobbyist or even just a beginner, you are probably aware of some pretty dangerous aquarium pests that can wreak havoc amongst your beloved marine life. Pests are something that every enthusiast will face at some time or another, so it is super important to be aware of what are the most common pests in saltwater aquariums, how to know what they look like, and what to do in order to get rid of them. In this article, we will discuss the 5 most common dangerous saltwater aquarium pests and what you need to do to get them out of your tank! 

Where Do Pests Come From?  

Unfortunately, no saltwater aquarium hobbyist is free from pests, no matter how good you are at keeping your tank clean! There are so many factors when it comes to aquarium pests and so many ways in which they get into your tank! 

The majority of pests hitchhike on coral or rocks or invertebrates. You might not able to see them, but when you put something new into your tank there might be a few little pests attached that are set on breeding and overpopulating your aquarium! This means, in order to make pests less likely to come into your tank, you should quarantine whatever you are planning on putting in your aquarium. You also must be sure that you are purchasing your rocks, coral, and marine life from reputable stores, like ours

Top Dangerous Aquarium Pests and How To Get Rid Of Them

So, even if you buy from reputable stores and you quarantine and you clean your new rocks and corals, you might still get pests. It doesn’t mean you have done anything wrong, these pests are called pests for a reason! They are determined and they can be very, very sneaky. But don’t worry, you can get rid of them. 


Flatworms are a really common aquarium pest but can cause very serious issues. There are different types of flatworms, but the two most common types are Acropora eating flatworms and rust-brown flatworms. Rust-brown flatworms are about a quarter of an inch long and brown with a red dot. They can cause issues for your corals as they will sit on them and block light. This means that your corals will not get the nutrients they need. They are found sitting on top of your corals or where there is a low water flow. 

The Acropora is not as common as the rust-brown flatworm, however, the damage they cause to saltwater aquariums can be very difficult to reverse. The main issue with these flatworms is that they are not that easy to see and therefore they can quickly overrun your tank. You will normally find out that you have these flatworms in your tank by seeing white marks on your Acropora coral. This is damage from where the flatworms have eaten them. 

In order to treat flatworms in your saltwater aquarium, you can choose the dip method, where you take the infected coral and dip it into freshwater for five to ten seconds and shake the coral underwater. This will cause the flatworms to fall off. You must make sure that the freshwater has the same temperature and pH as your saltwater aquarium! 

This does work, however, their eggs might be left on the coral. This means more flatworms. Because of this, we advise looking into bringing marine life that eats flatworms into your aquarium. Yellow wrasses, leopard wrasses, and certain dragonettes will eat the flatworms and are really cool fish, so this might be an option if you are suffering from flatworm issues. 


These anemones are a pretty common issue with saltwater aquariums, but can really impact the health of your tank. They are usually a brown color or clear with a long body and long stinging tentacles. They are really hardy, and multiply quickly! Because of this, they can soon overrun a saltwater aquarium. 

Because of how quickly they reproduce, they make the other marine life in your tank vulnerable. They will take food and space from other wildlife, and because of how long their tentacles are, they will sting and hurt corals and have the ability to kill them. 

When it comes to aiptasia, natural predators are the best way in order to deal with them. This means keeping your tank free from the pest, but not adding chemicals and disrupting the harmony of the tank. We advise adding a peppermint shrimp to your tank for this issue, as these creatures love to eat aiptasia and debris. They are also super easy to look after and reef safe. 

If this isn’t for you, you can choose to inject the aiptasia with something that will kill them. You can buy products that are specifically for getting rid of aiptasia, or use lemon juice. These treatments must be injected at the base of the anemone. If you choose to use this to get rid of aiptasia, please remember to watch out for your corals and their reaction to the chemicals that are in the water. Always do chemical treatment extremely slowly and carefully, checking the water chemicals regularly. 

Red Bugs 

Red bugs are tiny crustaceans that infect Acropora corals. They irritate the corals and cause them to retract their polyps. Because Acropora corals are pretty sensitive, something like red bugs can really affect their overall health. This means that the corals will be more likely to suffer and die. 

You probably won’t be able to see the red bugs unless you look really closely, so always be aware of any changes to your Acropora’s behavior. If you are concerned about red bugs, try and get a closer look to see if there are any red spots on your Acropora. Examine the coral for a while to see if there is anything moving on its surface. 

There are a few ways of killing red bugs and many involve adding chemicals and treatment to the tank. A common way is to add a drug called Interceptor into the tank. This drug contains milbemycin oxime which is toxic to crustaceans. It can only be purchased from vets. However, because it is toxic to crustaceans it can kill all the beneficial invertebrates in your tank and it can really stress out fish. 

Because of this, we recommend adding the dragon face pipefish into your aquarium to keep the levels of red bugs low. These fish will keep themselves busy picking off the red bugs from your corals. They are pretty hardy fish, however, they are picky eaters, needing copepods, live rock, and macroalgae. They can be difficult for beginners to look after. 

Sundial Snails

These snails are small crustaceans with a swirly shell of black and white bands. They do look pretty, however, they can cause a lot of damage in your saltwater aquarium. These snails will eat your zoanthids and will hunt them out. If you do not have any zoanthids in your tank, they will move onto other corals. 

Watch out for these snails because they can cause huge destruction to your corals! They will damage the base of the polyp and feed on the fluids and tissues. The polyp will then fall off. Thankfully, these snails are really easy to get rid of, you just have to remove them. They don’t reproduce quickly, so simply removing them from the tank will solve the problem. 

Montipora-Eating Nudibranch 

There are a few different types of nudibranch that will feed off soft corals and cause damage,  but the worst and most dangerous is definitely the Montipora-Eating Nudibranch. This nudibranch is white and small, only growing to about ⅓ of an inch. They go after the tissue of the corals from the Montipora and Anacropora genus. 

This nudibranch can be really hard to spot as they are good at hiding and work from the bottom of the coral that they are eating. However, they breed quickly and eat the corals at a surprisingly fast speed! 

They are also quite difficult to get rid of, and once infected, they seem to return again and again. If your corals are suffering from this pest, you must move them into a quarantine tank with the correct water flow and light. Then dip them in treatment until you do not see any of the nudibranchs. This can take weeks. You might also need to scrape off the eggs from the corals. However, this still does not mean that all the eggs and nudibranchs are gone. They still might come back. 

If you are suffering from this reoccurring pest, you might want to look into natural predators. The Auriga Butterflyfish and the Golden Semilarvatus Butterflyfish are both said to sufficiently keep the levels of nudibranch in your tank low and are quite easy to look after. 

Final Thoughts

Saltwater aquarium pests are not only annoying, but they can also be really dangerous and kill corals. However, if you are knowledgeable about what to look out for, and how to treat them, you will soon become an expert in how to deal with pests! Good luck, and we are always here to help.