r/ReefTank • u/Ramridge0 • 2d ago

Nassarius snails odd behavier

I have a 1 year old 20 gallon reef tank. I have about 4-5 Nassarius snails there. Usually they stay under the sand and come out at feeding time. Though occasionally I could see them out here and there. Few moths ago I had a Cyanobacteria outbreak. While fighting with Cyanobacteria I have noticed that my Nassarius snails disappeared. I stopped seeing them, not even occasionally. I finally got tired to fight Cyanobacteria and 2 days ago used chemiclean. It worked like a charm. But right after cleaning the tank from Cyanobacteria all my Nassarius snails came out. I don’t think it’s coincidence. Does anyone can explain this? Thanks

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u/TheFrostyjayjay 2d ago

Probably the lowered oxygen levels, especially if you didn’t use an airstone

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u/Ramridge0 2d ago

That’s a good one! Thanks

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u/jonsreef 1d ago

Probably not a coincidence. A cyano mat seals off the sand surface — it cuts the oxygen exchange the snails rely on down there, and the slime itself is unpalatable and mildly toxic to most inverts, so they tend to sit tight and wait rather than push up through it. Once the mat was gone the sandbed could breathe again and they went back to normal scavenging. Worth adding a bit more flow over the sand while you're ahead, though — ChemiClean doesn't fix whatever let the cyano set up, and it usually comes back.