I hold all new live rock in a fishless system for 30 to 60 days. I might not do that though for live rock that was shipped damp and then “bucket cured”, but I don’t use that technique any longer.@Jay Hemdal
Live rock and and sand from the ocean easily vectors in disease. Would you add unfallowed live rock from any source into zoo systems you're responsible for? Your home system?
biosecurity applies to materials transfer among reef tanks
From oceanic sources it's even more likely to have animals that are direct vectors, = snails etc / see Jay's biosecurity article
Cured live rock, wet surfaces, can introduce tomonts across systems even if it doesn't have snails with fish diseases directly in the gut
When people remove all their fish to fallow a system, why do they do that if live rock/ sand / surfaces aren't a harbor? Simply removing fish would instantly starve the parasites if surfaces afforded no hiding and insulation places. It takes 45-90 days, so what happens if we move that live rock into someone else's tank on day 2
Live rock from a LFS system that also holds fish should for SURE be isolated from fish for at least 30 days, but 60 is safer.
The story I always tell is of the LFS that would “treat” their sick fish by moving them into their invert systems (with better water quality). Of course, all the inverts they sold out of there had the potential to carry pathogens to their customer’s tanks..