Ich is a parasite that is either there or it isn't. Fish are more susceptible to the parasite when they are stressed out or weak (moving, water parameters not right, etc). Because of this the stress of getting an animal to your house makes it susceptible. Ich is a cyclic parasite and there are stages where the animal is presenting (visible white spots) and stages where the animal is not presenting. Because they may not be presenting when you bring them home, you put them into your system and a couple of days later (as was the case with my PT) you see the first spots appear. The fish was affected before but moving exacerbated the problem and made the fish more easily attacked. My PT was at hypo (1.009) in QT
for 5 weeks. 4 weeks since the last known spot, 1 more week to bring the SG
back up to normal and 1 week of watching and waiting prior to release in the main (8 weeks total).
Presuming there is no ich in my main moving my now perfectly healthy PT into my main would not result in him becoming infested again. I suppose that there's always the chance that some other fish in my main was a carrier but never presented and that all of my perfectly healthy fish in my main are able to fight it off and that when I put my PT in from this next move he'll become susceptible, but at this point I've done everything that I can to prevent ich from getting into my main.
My 2 (now 3) tanks are kept at the same SG
, same pH (to the best of my ability) and same ro
+ salt mix. The water in the three tanks should be largely similar. I will acclimate the PT when I move him anyway, just probably not for very long.