Fenbendazole

[Cinnebuns]

I think I remember hearing that fenbendazole, as well as being toxic to all inverts, sticks around in a tank for 6+ months. Is this true?  I had dosed my 29 several months ago. I forgot and put some snails in it about 2-3 months later and they died. I then remembered that it can stick around. That's true right?  Does activated carbon or purigen help with that at all?  How long should I wait to add inverts back to that tank?  I also did dose the tank with no planaria but I don't think that one is the issue. Might be though?

@Colu @Odd Duck I have a feeling one or both of you might know this one. 

[Colu]

Fenbendazole is extremely toxic to snails  it can be absorbed by porous material such as rocks and leech out months later from what I have read  I would be very cautious about adding snails to a tank you have treated with fenbendazole no planaria active ingredient is betelnut Palm extract some conflicting information some saying it kills Ramshorns MTS and pond snails what I would do is run active carbon or purigen for a couple of months just in case any medication is leeching from porous material in your tank then I would add bladder snails or MTS to see how they do before add mystery or nerite snails @Cinnebuns

[Odd Duck]

I managed to unintentionally kill off the MTS colony in my pea puffer 29 G tank by dosing with No Planaria, so I would say, yes, it absolutely will kill snails.  How much of either hangs around is hard to say.  I suspect it would depend on substrate, types of wood, etc, in the tank when dosed.  I would take out and wash and scrub any wood, replace substrate or vacuum it very well, do big water changes, run activated carbon, etc, to try and get it all out as much as possible.  Only test with snails you’re willing to risk, so no nerites, rabbits, or other expensive snails.  Test with “pest” snails before risking expensive ones.

[Guppysnail]

On 7/25/2023 at 9:53 AM, Odd Duck said:

Only test with snails you’re willing to risk, so no nerites, rabbits, or other expensive snails.  Test with “pest” snails before risking expensive ones.

For what it’s worth here is my experience my with fenbendazole. 
 

Some bladder and pond snails do survive and their Eggs survive.  
Mystery snails are usually safe a few weeks after fenben is water changed out and carbon run as long as the substrate is gravel or sand. Eco complete and many other active substrates will absorb and continuously release the FB same with wood and some fast growing plants. As @Odd Duck said remove and scrub what you can.  Plants use Reverse Respiration if possible during FB treatment. 
Nerites are hypersensitive to FB unlike pest and mystery snails in my experience. I have waited as much as 3 months before returning nerites to a treated tank and still had issues. 6 months I’ve not had issues. 

Side note in plants. On 1 occasion my plants went through FB treatment. After the treatment was done roughly a week later I pulled some hornwort out of the tank and moved it to another tank. 3 of my nerites were affected in the new tank. I’m guessing because the hornwort chose to drop a lot of needles maybe?  Assasin snails in that tank including babies were not affected. 
 

Sorry I don’t have definitive answers but maybe my experiences can assist in guide posts. 
 

[Cinnebuns]

On 7/25/2023 at 8:53 AM, Odd Duck said:

I managed to unintentionally kill off the MTS colony in my pea puffer 29 G tank by dosing with No Planaria, so I would say, yes, it absolutely will kill snails.  How much of either hangs around is hard to say.  I suspect it would depend on substrate, types of wood, etc, in the tank when dosed.  I would take out and wash and scrub any wood, replace substrate or vacuum it very well, do big water changes, run activated carbon, etc, to try and get it all out as much as possible.  Only test with snails you’re willing to risk, so no nerites, rabbits, or other expensive snails.  Test with “pest” snails before risking expensive ones.

No planaria is shrimp safe tho right?

[Odd Duck]

Yes, it appears to be.