I used to be a Risk Taker. Never did quarentine, just the proper acclimation to reduce fish stress.
I got away with taking risks for 10 years+. LUCKY ME eh?
Built up some nice fish stock and the fish grew up under my care.
The fish became very used to me and vise versa. I got attached to them....Especially my Powder Blue Tang.
Nothing went wrong even during, minor mishaps, power failures, tank tear downs and rebuilds.
THEN ONE Day, I had a freak accident and lost a one clown from a Pair.
The other clown instantly got lethargic. Kind of depressed.
I rushed to get a replacement clown to make him/her happy.
Found a perfect match and tossed him in to join the other Clown. (no QT).
That's when my years of luck ended, to become the worst experience of my Life in this hobby.
One by one the fish started dieing. I had no experience on disease recognition, to react fast.
I had no QT or Hospital setup to remove or treat fish. No meds.
Sure I reached out for help and got plenty from the forums.
The disease looked to be Velvet.
Fish kept dieing, one by one.
Watching the Slow Suffering Deaths of my Fish was devastating.
My heart broke when my Buddy of 10 years.... the Powder Blue Tang started dying.
He was last to die since the Largest and strongest fish. I learned a lesson I wish I didn't have to learn.
The tank had to go into Fallow for 3 months and eventually I did get fish again.
I now QT each and every time. Even from stores that Treat Fish with Meds.
It saved me already twice since I caught a disease that I didn't introduce to my Healthy Tanks.
I have 3 Tanks and on occasion I've moved fish between them, with confidence I have clean stock.
Point is....If you have one fish, QT may not be needed as much.
The loss and pain increases as you build up a healthy stock of fish.
Just search on the Forum under fish Disease. Read the reactions and feelings people go thru when things go bad (not doing QT).
You'll get a feeling what it's like.
It's personal decision you have the right to do as you wish. This risk is yours.
Just be aware, when your luck runs out, you may regret it Big Time like I did.