"You should be able to get them rehydrated after one or two showers. "
I realize this says SHOULD. However, I think this is a misleading statement. Severely dehydrated animals (with fully curled tails) can take weeks to completely re-hydrate. It may only take a few showers to flatten the tail, but you have to continue to watch them, as this is usually a temporary thing and they will revert to a dehydrated state again very quickly.
It is a good practice to shower at least 2x a week (daily if visibly dehydrated) for the quarantine period (at least 60 days), and once a week after that for maintenance purposes. Fimbriatus are pretty famous for looking fine one day, and the next looking like they've had nothing to drink in a week.
Good luck.
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