i used to transport live fish before but the distance and
time is much less than what you have indicated. we travel
around 4 to 6 hours and our merchandise is more delicate than
oscar. they were live grouper for hotel's supply. the process:
we put big plastic bag in styro box, filled with cycled salt water,
put the fishes, inflate with oxygen, tied and sealed the opening
of plastic bag, put the cover of the box, and ready to roll.
in some ocasion, we had mechanical trouble and stayed overnight
along the road, the following day, we delivered and found out that
all supplies were in good condition. that is more than 24 hours.
the only difference was that there was no motion while waiting for
the back up truck.
just giving you the idea. nevertheless, i agree with DadMac.