I didn't QT for about two years after coming back to the hobby. Never had any problems - but I was never a person to impulse buy fish, or purchase fish from diseased tanks. My methodology was to find a fish I wanted at an LFS, and have them hold it as long as possible. If it was still in good health in two weeks or therabouts, I'd bring it home and acclimate it to my DT.
Ironically, it was only after I started to QT fish that I had a disaster. It wasn't because of the QT though - I bought a hard-to-find pair of fish that I had never been able to get before the day they came into the LFS. Two days later, not only were mine dead with no visible signs of illness, but the entire batch that the store had gotten were also dead, and their stock tank was now quarantined and mostly empty.
The disaster came when I failed to sterilize my equipment thoroughly and contaminated the DT. I lost all seven of my oldest fish (also difficult to find) in the span of two months after repeatedly fighting off the illness only to have it come back again and again.
The lesson I learned was that before you even decide to QT or not, you need to start making good decisions about the fish you purchase. To that end;
- Avoid getting fish from tanks with sick/dead fish (obviously)
- Observe the fish you want for a while, and observe their tankmates. Watch for suspicious behavior that you wouldn't notice at a glance
- Pick out a fish and let it marinate if you can. Try to avoid picking up brand new fish that just finished their journey to the LFS
- If you absolutely cannot wait for whatever reason, then you get it and QT it
Two years of not quarantining fish and I never had any problems. The day I broke my own rule (of purchasing newly arrived fish due to the rarity of them) was the day I signed the death certificate for my 2+ year old flock of catfish.
So, before you even need the ask the question of "do I need to quarantine?", you need to start making smart choices
