Our bettas and assorted african cichlids both get shipped in smaller bags, placed in a larger bag. Saves on them killing eachother is my only guess. I'm no betta expert, and apparently I have been misinformed about bettas. I was told, and read an article titled "Bettas are better in bowls".
Due to Bettas being loners, it states they get / stay stressed in bigger aquariums with other fish, especially those resembling other males. Also that filtration in a bigger tank will not allow them to make their "bubble nests".
Now, please don't flame me, this is what I was "taught" and read in that article. These bettas aren't used to the amount of other fishes that occupy a bigger tank.
If anyone has a real precise, and informative site about bettas they can post, I'd be happy to read and understand them more, even if it DOES mean going against everything I was taught in my LFS about them. Yes, I work at my LFS, but only for a bit under 3 months... so I'm still learning, and would like to actually, know something to be fact, than to hear word-of-mouth information about our pets. Unfortunately, I already know a bit more than some of the others about a few of our animals, and I'm wanting to continue that. I don't want to be one of these "this dumbass at my LFS said this" guys.