How to Identify The Most Common Live Rock Hitchhikers

Live rock is basically old pieces of reef that is broken up into aquarium sized pieces and is used for decoration and filtration in reef and saltwater aquariums. Often times the live rock is shipped directly from a collection facility to your local retailer, and then made available to you. This fresh live rock is almost guaranteed to have "hitchhikers" on it, little marine critters living in and on the rock. Some of these hitchhikers are beneficial to your ref, but others can quickly become a nuisance. To help you identify the most common live rock hitchhikers, we have complied this list of the good, the bad and the ugly!


blue spongeSponges: These filter feeders come in a variety of colors and shapes, and can really add aesthetic beauty to your reef. Be mindful that a sponge colony does not grow out of control.

Cerith SnailsSnails: These gastropods are generally good and help your clean up crew. A special bonus if you get a cowrie! Watch out for predatory snails that attack corals and other clean up critters.

CopepodsCopepods: These planktonic crustaceans can be a real boon to your reef as they can provide a regular stream of live food for picky eaters such as long nose butterflyfish. To keep the copepods growing in your tank, set up a refugium with chaetomorpha.

mini brittle starMini Brittle Stars: These echinoderms are a welcome addition to your clean up crew and will readily devour detritus and other waste in your reef tank.


pistol shrimpShrimps: These crustaceans are not common on live rock, however pistols shrimps and mantis shrimps have been reported on live rock. Be on the look out for these pesky critters when adding new live rock to your system.

acro eating crabCrabs: While some crabs are good (ie; red leg hermit crabs), others can be a real problem. Some of these cantankerous crustaceans can attack fish and other members of your clean up crew, while others will eat your corals! If you spot a crab and are not sure if it is friend or foe, snap a photo and post it up to an online reef club for help identifying it.


bristle wormBristleworms: These polychaete marine worms can be difficult to spot as they often burrow into the rock and sand, and only come out at night. Be careful as some of these can deliver a painful sting if they come in contact with your skin.

aiptasiaAnemones: These sessile polyps can be a nightmare. On the aquarists most unwanted offenders list is the Aiptasia and Majano anemones. If you find either of these on your live rock, remove it immediately and treat the rock to terminate the unwanted anemones with extreme prejudice.

bubble algaeAlgae: Most live rock is crusted in desirable purple coraline algae, however the pesky green types of algae like hair algae, bubble algae and caulerpa are often introduced to reef aquariums on live rock at the outset. Further fueled by rampant phosphates and nitrates, these ugly hitchhikers can quickly turn your dream reef into a nightmare.

zoa eating nudibranchNudibranchs: While some of these mollusks can be colorful and lovely to look at, the drab, unassuming ones can cause the most damage! Be on the lookout for zoanthid, sarcophyton, montipora and even acropora eating nudibranchs. They can get into your reef unnoticed and decimate your precious corals!