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Saltwater Aquarium/Strange growth on my clam


clam growth
clam growth  
Hi David,

I have been in the hobby for 20+ years and have never seen this before. My job moved to China recently and of course I started a reef as soon as possible. This tank is about 6 weeks old. In China when you buy a tank it is deliver to your home completely set up as it was in the shop including water and livestock so I got the clam with the tank. The clam is doing great but this thing started to grow on it in the first week and it grows fast. I have no idea what it is or if it poses any treat to the reef. It is some sort of filter feeder and it does not bother the clam, it runs along the side of the clam from the foot to up under the mantel.
Please let me know what it is.
Thanks for your help.


Hi Ed:

It's nothing to be alarmed about; it's common for marine invertebrate and other marine organisms to live on the exterior of a clam. These may include sponges, coralline algae, macro algae, marine plants, small corals, and pods, just to name a few. Marine zoologists believe these marine animals/organisms as well as the clam interact with each other (symbiosis) to help feed and protect each other in various ways.

From your image it appears to be a sponge growing on it.

I wish you luck with all your saltwater aquarium endeavors.


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David Ocreef


Technical saltwater coral reef related aquarium questions are welcome. Coral, invertebrate, and peaceful species of saltwater fish questions are welcome. Questions asked on Saturday and Sunday will be answered the following Monday. REMINDER: Please check the answers pool to see if your question has already been asked and answered. Questions typically are answered within a 48 hour period, however sometimes it may take longer.


I possess over twenty-five years of hands-on experience and knowledge in the ecology of aquariums. Beyond the traditional, I have successfully tested and sustained environments that have been uncharted territories for hobbyists, for decades. I am the first to admit I don't know it all because there will always be something new, amazing, and exciting to learn about, as discoveries are made. It's a hobby one can never outgrow, or grow tired of.

MASNA - Marine Aquarium Society of North America. Director of Orange County Reef Aquatics -

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After High School, my experience and love of marine animals influenced me to take up studies in Marine Biology. Throughout college, I studied Microbiology with an emphasis on Marine Life, as well as numerous other sciences. I continued to advance in this hobby, by building a dozen or more saltwater ecosystems all utilizing Microbes as the major source of my filtration method.

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