Top 10 Most Common Live Rock Hitchhikers

What’s up Salt-Nation? Jeff here, and lets jump right into it today with an article on the good, the bad and the ugly that comes with live rock hitchhikers. If you have ever set up a saltwater aquarium, you’re aware of the possible live rock hitchhikers that can come with Live rock. Live rock is generally a piece of reef rock that is harvested from wild reefs and is used for aquascaping in saltwater aquariums.

What are Live Rock Hitchhikers?

The reason that live rock is referred to “live rock” is because of the life that comes with it from the reef. This life can be beneficial or a down right nightmare. After harvesting the rock it is shipped wet to preserve the life that lives on the rock. Along with beneficial bacteria, often small animals and other organisms survive the trek. In the aquarium hobby, they are most commonly referred to as “live rock hitchhikers.

The list that follows includes some of the most common live rock hitchhikers hobbyists may discover with their aquarium live rock. Our goal is to help you identify these organisms and teach you how they can affect your aquarium, for better or worse.

Top 10 Most Common Live Rock Hitchhikers:
bristle worm

#10 Bristle Worms: They can range in size from under an inch to being 2 feet long.  Smaller specimens commonly seen in aquaria which usually range from 1″-6″ in length are usually pink in color while larger specimens sometimes encountered are frequently gray or brown in color. Can be beneficial in low populations and when smaller in size, larger bristle worms have been known to kill small fish.

#9 Watercress Alga: Thick profusly branched clumps of rounded three lobed or ribbed leaf like segments. Dark to bright green and yellowish green. They almost look like a cactus and are an attractive ornament algae that doesn’t usually last long in a saltwater aquarium.

#8 Social Feather Duster: Grow in clusters, crowns extend from exposed parchment like tubes, circular crows white, tan, brown or purple often two toned with dark centers. For the most part they are harmless filter feeders but they can grow anywhere in an aquarium and in abundance if not put in check.

#7 Flat Worms: Small reddish-rust colored creatures. They may appear on the glass/acrylic, on the substrate, or on live rock. They feed on small foods like rotifers, phytoplankton and will grow out of control, if unchecked. If they get to the point of overpopulating the tank, there is the possibility that they may die suddenly all at once, and the toxin they release at death can cause the aquarium to crash.

#6 Tube Coral: Colonies form small densely branching clumps. Branches have fine ridges running their length, and each ends with a singular corallite. Tan to golden brown and dark brown. They can often found living on fresh high quality live rock.

#5 Key Hole Limpet: Their shells have a hole at the tip for respiration That’s where they get their name. This opening at the top allows a direct exit of exhalant water currents together with waste products from the mantle cavity. The water enters under the edge of the shell near the head and passes over it’s gills. Key hole limpets are algae eating machines.

#4 Sponges: are a unique organism similar to, but not quite, coral. They filter food from water and are usually non-photosynthetic. They tend to grow then disappear for no apparent reason. This may be due to the lack of suitable food sources in the aquarium. Contact with air can also kill sponges as well.


#3 Aiptasia: Or glass anemones are light brown/pink in color and semi-transparent. They can start out small, around ¼” to ½” in diameter, but can grow to 1 ½” to 2″ if left uncontrolled. They are photosynthetic and will fully expand during daylight hours. They can also take over an aquarium in the right conditions. larger Aiptasia have the ability to kill and eat small pray such as fish and shrimp.

#2 Brittle Starfish: These echinoderms are a great addition to the clean up crew in your saltwater aquarium. Brittle starfish will readily devour detritus and other waste in your reef tank.

#1 Copepods: Copepods are planktonic crustaceans and are an amazing addition to your aquarium. They are a regular stream of live food for picky eaters. Hobbyist go as far to introduce copepods to their aquariums intentionally and keep a refugium in the aquarium sump, to promote growth.

Live Rock Hitchhikers Final Thoughts

Remember, One of the most important steps in setting up a saltwater aquarium is adding live rock and using rock from the ocean may not be the right Decision for everyone. Ask the right questions and do your research. Now I would like to invite you to look around Mad Hatter’s Reef, We have a lot of information for people looking to get into the hobby and old salty hobbyist too. I wish you luck on your salty venture and let me know if you need anything.

Feel free to drop me a line at:

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