Of course there are opinions advocating shorter QT periods out there, I have a pretty extensive library, can't find anyone in print advocating 6 weeks as an absolute limit, I'd be interested in knowing if there is something out there I have missed.
Paletta. The New Marine Aquarium, 1999, p. 114
"Every new fish, whether given a dip treatment or not, should be placed in the quarantine tank for 3 to 4 weeks"
Dakin, The Book of the Marine Aquarium, 2003, p. 147
"When the fish has been quarantined for the full 3 week period, and you are entirely satisfied with its health, introduce it into the main aquarium"
Fenner, The Conscientious Marine Aquarist, 2001, p. 154
"A proper interval (generally a minimum of 2 weeks) must go by in which the specimen in the quarantine tank shows no ill effects of transport or disease. Some public aquariums wait 4 weeks for additional security"
Delbeek & Sprung, The Reef Aquarium, vol 3, 2005. p. 646
"Three to six weeks is usually a sufficient quarantine at this salinity level"---(referencing hyposalinity QT...JC)
Spotte, Fish and Invertebrate Culture, 1979, p. 123
"New stocks of animals should not be added to the main water systems until they have been isolated (quarantined) and have proved to be free of infections (microorganisms)or infestations (macroorganisms) for 4 weeks"
And last but not least, the ultimate authority:
Skomal, Saltwater Aquariums for Dummies, 2002, p. 185
"Serious aquarists establish a quarantine tank for their new fishes to inhabit for a few days to evaluate the health of the fish".
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