We don't have Petco here :P
I work at one of the biggest fish shops in my country, We recived the betta shipment from Vietnam.
Here is the bag, I took 2 of the fish that arrived and gonna take a third one tomorrow(he's in a really bad shape) Dumbass guy who shipped them thought it would be funny to overfeed a few of them.. (It's a rosetail butterfly, red white and transparent) He prolly won't be staying with me but I will give the forum first dibs if someone wants him(I have a license to import and export betta fish :) ) 4-5 of them came in bags of poop.. 2 I took home and 2 I started treating in a small bowl in the shop, I know they arn't cold there but I want to treat them in a heated 5g with a filter.
Anyway long story short here is the bag, the water is at 2/3 the fish(shanks modeling in the back for your convenience) and it's tight sealed with air inside.
The thing in the upper part is a piece of paper that keeps it from sticking to itself when air depletes..