As soon as you have fish in your tank you will need to have a catch net (also called an aquarium fish net) in order to move your fish around, and remove any dead fish from the aquarium.
Your hands may inadvertently have bad bacteria on them that could make your fish sick, so it is always a good idea to rather use your fish net when taking anything out of the fish tank.
Some Aquarists suggest that you have a set of tools (fish nets, buckets, containers, etcâ€¦) for each tank you own.
I tend to agree with this in principle, since a contaminated aqarium net from one tank, may infect a clean tank.
In reality most aquarium hobbyists cannot afford to have so many sets of aquarium tools.
What I suggest instead is that you use your one net in a sequence:
First use it in your healthy tanks, and then your quarantine tank, and only then your hospital tank.
Once you have completed using your equipment soak them in very hot water, with some salt mixed in.
This does not completely avoid transmitting disease, but does reduce the likelihood quite a bit.