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Common Saltwater Aquarium Hitchhikers

by Brian Dunleavy
Common Saltwater Aquarium Hitchhikers

Are you a proud aquarium owner? Do you love to watch your aquatic pets swim around in their beautiful underwater world? If so, then you may have encountered some unexpected guests in your aquarium from time to time. These are commonly known as "aquarium hitchhikers" and they can come in many forms. 


What Are Aquarium Hitchhikers?

Aquarium hitchhikers are organisms that inadvertently find their way into aquariums, usually by attaching themselves to decorations, live rock, or even the creatures that are intentionally introduced into your tank.

While some hitchhikers are harmless and even beneficial, others can wreak havoc on the delicate ecosystem of the aquarium. These unwanted hitchhikers are commonly referred to as aquarium pests. 


Bobbit Worms & Fireworms 

Bobbit Worms and Fireworms are two of the most common hitchhikers that can be found in aquariums. While they may seem harmless at first, these creatures can quickly become a major problem if they are not properly managed. 

Bobbit Worms are known for their long, slender bodies that can grow up to three feet in length. They are also equipped with sharp teeth that they use to catch and eat their prey. While they are not typically aggressive towards humans, they can cause serious damage to fish inside your aquarium. Fireworms, on the other hand, are much smaller in size, but they can still cause significant damage to corals and other invertebrates in the tank.

One of the biggest challenges when it comes to dealing with Bobbit Worms and Fireworms is that they are incredibly difficult to remove once they have established themselves in the tank. They are often able to hide in the substrate or within the rocks, making it difficult to spot them. Additionally, they are both extremely resilient creatures, which means that traditional removal methods such as chemical treatments may not be effective.

The best way to deal with Bobbit Worms and Fireworms is to prevent them from entering your tank in the first place. This can be done by thoroughly inspecting any new additions to your tank, including live rock and other decorations. It is also important to quarantine any new fish or invertebrates for a period of time before introducing them into the tank. If you do find that Bobbit Worms or Fireworms have already established themselves in your tank, it is important to seek the advice of a professional aquarium specialist to determine the best course of action.


Gorilla Crabs

Gorilla crabs are named for their large, hairy claws which resemble those of a gorilla.

While aquarium gorilla crabs can be a fascinating addition to any tank, it is important to note that they can also be pests if not properly cared for. These crabs are opportunistic feeders and will often prey on smaller fish and invertebrates in the tank. 

They can also be aggressive and territorial, making them a nuisance to other inhabitants. The good news is that removing gorilla crabs from your tank is a relatively simple process.

First, you'll want to catch the gorilla crab using a net. Be sure to wear gloves as these crabs are known to have sharp claws that can inflict painful pinches. Once you've caught the crab, you can either relocate it to a different tank or dispose of it. If you choose to dispose of the crab, be sure to do so humanely.

It's also important to note that prevention is key when it comes to gorilla crabs. These crabs are often introduced to aquariums via live rock or other aquatic decorations. Be sure to quarantine any new additions to your tank before adding them to ensure they're free from unwanted pests.


Aiptasia & Majano Anemones 

Aiptasia and Majano Anemones are tiny creatures that may seem harmless at first, but they can quickly take over an aquarium and cause havoc for its inhabitants.

Aiptasia Anemones are small, brownish, and translucent creatures that can quickly multiply and become a pest. They are commonly known as glass anemones or rock anemones, and they attach themselves to live rock, corals, and other surfaces in the aquarium. Aiptasia Anemones are known to reproduce both sexually and asexually, making them a difficult problem to solve once they have taken hold in an aquarium. They can sting and harm other corals in the tank, making them a nuisance for any reef keeper.

Majano Anemones are similar in appearance to Aiptasia Anemones, but they are typically smaller and have a more uniform shape. They are also known as button polyps or coral-eating anemones. Majano Anemones can be a particular problem in smaller aquariums, as they can quickly multiply and overtake the entire tank. They are known to sting and harm other corals in the tank, making them a pest for any aquarium keeper. The best removal method is to physically remove them or use a chemical method containing calcium hydroxide. 


Mantis Shrimp

The mantis shrimp is a fascinating creature that is often admired for its vibrant colors and unique features. These crustaceans are known to be aggressive predators and are sometimes kept in aquariums by enthusiasts. However, there are times when a mantis shrimp can enter an aquarium as an uninvited hitchhiker, and this can be a cause for concern.

Mantis shrimp hitchhikers in aquariums can pose a threat to other marine life in the tank. They are known to be territorial and can attack and kill other fish and invertebrates. This can lead to a significant loss of marine life and can also disrupt the balance of the ecosystem in the tank.

If you suspect that a mantis shrimp has entered your aquarium as a hitchhiker, it is essential to act quickly. The best way to remove a mantis shrimp from an aquarium is to lure it into a trap using bait. 



Bristleworms are often introduced into an aquarium through live rock or sand, where they can hide and reproduce undetected. They feed on detritus and other small organisms, and can actually be beneficial to the aquarium environment by helping to keep it clean. However, if their population grows too large, they can become a nuisance, and may even prey on other inhabitants of the aquarium. 

There are a few ways to control the population of bristleworms in an aquarium. One option is to manually remove them using a pair of tongs or tweezers. Another option is to introduce predators that will eat the bristleworms, such as arrow crabs or certain types of fish. However, it's important to do your research before introducing any new species into your aquarium, as some predators may also harm other inhabitants. 



Aquarium hitchhikers are organisms that inadvertently find their way into aquariums and can cause harm to the delicate ecosystem. While some hitchhikers do not cause havoc, some will, and therefore you must follow suitable removal and preventative measures. 

If you are having difficulty with hitchhikers inside your aquarium, feel free to contact our experienced team at Reefco Aquariums!

by Brian Dunleavy