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Saltwater Aquarium/Engineer Goby Shedding?


I recently moved my adult engineer goby from my 30 gal tank to my 75 gal tank due to it outgrowing the smaller tank. This was about 3 weeks ago. 4 days ago I had a pearl scale butterfly die in that tank right before my shipment of a sand sifting star and an emeral crab were scheduled to arrive. Tonight my engineer goby emerged from his cave and has been swimming around out in the open which is not typical behavior for them. I noticed also that he has what appears to be shedding going on and no apparent injuries. This "shed" looks just like when my ball python sheds and covers the majority of his body except for a portion of his tail which the "skin shed" is hanging off of. I googled it and some others say it's likely a fungal infection. I transferred over my large cleaner shrimp to the tank with the goby in hopes that it would be able to help clean whatever it is off of him. They had a very successful symbiotic relationship in the 30 gal tank so hopefully he can. What are your suggestions for what to do next?

Hi Joshua:

The Engineer Goby will surround itself in a mucous cocoon (that they produce from their own body), they do this when sand is not present in the aquarium, or when not enough sand in the aquarium is present. Gobies survive best with deep sand beds, that they use to make homes / burrows into.

Deep sand beds are what they use to escape predation in nature. Therefore if your aquarium is lacking sand, then your Goby fish will produce this mucus cacoon around itself every night, which helps with not only a sort of camouflage, but it hides the scent of the fish in an effort to ward off predation, by keeping predator fish from finding it and eating it. This is how these rather smaller species of fish have survived for thousands of years in nature, by using survival techniques like this.

In conclusion the mucus is harmless, and is no cause for alarm, nor is it a fungus or bacteria. It can be easily removed from the aquarium when found discarded by your Goby.

My recommendation is to add a quality fine-grade reef sand to your aquarium.

I wish you the best with all of your future saltwater aquarium endeavors.

David - All Experts
Director - Orange County Reef Aquarium  

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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 -

Publications,, and many others.

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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