Hi all I had a hydra infestation in 2 of my tanks (my 5g and my 15g). I had planned to turn the 5g into a shrimp tank (which I have now done) and the 15g had fry and tiny fish that were getting stung by the hydra. I tried a few ways to get rid of the hydra naturally, but alas it didn't work so I decided to treat with pancur (fenbendazole). I knew there was a risk to snails with this treatment so I moved my mystery snail and my spixi snails to a qt tank while treating. Once the hydra was gone I did a big water change and added carbon to the filter to clear the remaining meds. After a few days I added the snails back in to the 15g. The mystery snail appeared to get more and more lethargic, eating less even when I put in his favourite foods. There was a gradual decline over about 1-2 months. In the mean time I also converted the 5g (which was a well established tank) into a shrimp tank. I also added a nerite. From day 1 the nerite was withdrawn. I had it for about 9 days and then it died. Today my mystery snail has also died. I've also found empty pest snail shells throughout both tanks since the fenbendazole treatement, so I believe these deaths are connected. I'm sad and frustrated. I used the qt to avoid harm to the snails, but I'm wondering whether some of the meds leached into the substrate or silicon. If I could turn back time I'd remove all the fish and use heat, but I thought quaranteening the snails would be easier. I guess i was wrong. I will be keeping a close eye on my spixis as I don't want to lose them as well, but they have been acting strangely, so I fear them may also be impacted. If you have hydra and you have special snails I would strongly advise against the fendendazole treatement.