I purchased two of the plants from a vendor that wasn't selling any dart frogs. Or any amphibians for that matter. They acted like they were dying, so I put them each in their own quarantine container and they started acting normal again within hours. I put them back in the viv, and the exact same thing happened again, except one died. So I went out, bought new plants, new soil, and new leaf litter. I put them back in the viv again, and the two surviving frogs are doing great now.