I put three Assassin Snails in a Fluval Edge (6 Gallon) to "control" a Ramshorn outbreak that was about 120 snails by the time I got the Assassins in there. I figured the Assassins would control them at levels I could tolerate.
Well... they killed them ALL in 3 days. Tank floor was littered with empty shells. Snails that hatched were eaten too. I actually go to the LFS now and get their outbreak snails to feed them every few weeks. MTS, Pond, Ramshorn...... they kill them all. I'm going to have to separate them to slow them down.

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Crystal Red and Black, Red Claw Macros, Red Cherrys, Green Shrimp, Sulawesi Malawa, Blue Pearls, CPO, Dwarf Crays (C. shufeldtii), South America Puffers, Assassin Snails, Ramshorn and Pond Snails, Hawaiian Actinic Shrimp (Halocaridina rubra), Nerites