Ive never heard of a 76 week (or day) quarantine.
You can catch the majority of potential catastrophies in ~4 weeks between copper and prazi, as well as observe for behavioral issues that could result in livestock death.
At my old LFS, every fish went through these 4+ weeks of qt and medication before moving to the showroom/store and sold to public. Few-None LFS's do this in Atlanta. The majority (maybe 75-95%) of fish direct from wholesalers were infected with one thing or another, depending on type of fish. The vast majority of Tangs had ich. Worm (of various types) infections were also very common. Other ailments were not rare, just less common than ich or worms.
Inverts were not qt'd.... just inspected on arrival and observed/remedied in isolated systems.
Corals are dipped, at least once, with 24-48 hours between dips. For dipping, do full concentration, but dont surprass recommended time limits for your dip. Halfway through, begin to blast the coral and all crevices with water. I use a pipette. This will dislodge weakened pests, as many dips wont kill 100%... but it will weaken them enough to not hold on tightly.
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