Vermetid snails have been defined as a harmless mobile mesogastropods that worm their way into our reef tanks. Unlike most mobile mesogastropods, vermetids reproduce by means of the male of the species releasing spermatophores, which are then caught by nearby female’s mucous nets. Once females catch the spermatophores, they store the sperm until they are ready to fertilize their eggs. The vermetid's young remain inside the females’ tubes until they are reared through various stages and are ready to crawl out. The Vermetid young usually only crawl a short distance before attaching themselves and begin their new life as another pest in your tank. I also believe that some vermetids are swept via power heads, closed loop and sump return pump flow currents to various other places inside the aquarium.

I have found that vermetids grow rapidly in aquarium plumbing and hard to get to areas of the sump. They can cause problems by restricting flow through various pipes and cause obstructions which can hamper drains and cause surging in plumbing lines. In addition, their tubes are sharp and can cause injury to the hobbyist while working in the tank. Thinner aquarium gloves can be easily torn by the vermetid tubes.

Vermetid snails can also cause problems with aquarium inhabitants and smother corals, killing them. From my experience, Vermetid snails feed by shooting small web-like mucus tissues from inside their tubes. Often times these webs are small and hard to notice. Other times, such as feeding the tank and disrupting the sand bed, will cause the webs to extend fully. I have noticed that some of the mucus webs extended over eight inches. As my vermetid population grew I noted that at feeding time, it appeared that there were very dense spider webs which covered rock and coral. It was obvious that these mucus webs irritated the polyps which in return caused the polyps to retract.

The first corals that were affected by the vermetid's constant irritation were a wonderful colony of zoos. I noted that the zoos closest to the tubes closed up first and never reopened. It was only a matter of a week and the entire zoo colony was wiped out. Additionally I noted that the vermetids irritated three colonies of birds nest (Seriatopora hystrix) which also began to close up its polyps and then subsequently STN'd. Due to the static and properly maintained parameters of my reef, I do contribute the decline and death of these corals to the exploding vermetid population.

Due to the size of my tank at the time, 370 gallons (8'X2.5'X2.5') manual removal of these pests was impossible. In addition the population of the vermetids absolutely exploded. I literally had hundreds of thousands of them. I tried a Copper banded Butterfly fish which others have had luck controlling these pests without success. I was also advised to try various chemical treatments intended to kill snails, but elected not to use them as I don't believe in adding such items to my display. This compiled with other life issues, forced me to tear the 450 gallon system down. As luck would have it, I moved all the livestock and approximately 100 lbs of live rock (vermetids included) into my 125 gallon tank. To my surprise, six months later I noted that a vast majority of the tubes were chewed down to their base. After spending a few weeks closely examining the happenings in the tank, I found that a lone zebra leg hermit crab was feeding on them.

So in closing, I would suggest that the vermetid snails be treated as a serious pest in the marine aquarium environment. Once introduced the possibility of them becoming an expensive and frustrating pest is likely. The good news is that some have reported success controlling them with copper banded butterfly fish, various wrasses and apparently crabs.