I use to work at a state trout hatchery.
There were no sedatives
In fact, trout meant to go out to be stocked were not feed at all for a week prior
This was to avoid any motion sickness and keep them from puking up food in the stocking truck tanks. The lack of oxygen from the fouled water would kill all the fish before they arrived at their destination.
The stocked trout don't spread out very quickly, mostly because they've lived their short lives confined to a small area.
Once they get their act together, they are ravenous and will eat most anything that looks good.
But they quick learn what's editable and what's not.
They never forget the sound of the food pellets hitting the water though.
One old trick is to gather up a small handful of sand and toss it in the water.
Then quickly toss a dry fly in to the mix
Will it work ?.... you won't know unless you try
The simpler the outfit, the more skill it takes to manage it, and the more pleasure one gets in his achievements.” --- Horace Kephart