Hi:
Almost all of the banggai you see in thg LFS are WILDCAUGHT.
It has been suggested over the past yr or so that banggais have been wiped out of their original locale (the banggai island, sulawesi). There has been a recent suvey done to account for the species, and we are waiting the results (crossing my fingers of course).
W/ that said. Banggais are fairly easy to breed, but that does NOT make them good fish for aquaculuture, mainly becuz they have very small broods, and high tank demands(like one brood/tank)making these fish expensive to sell.
The banggai fry while larger than many other fish fry seem to be troublesome to many hobbyists, and becuz of this, the fish in underrepresented in breeding programs.
So this is why wildcaught fish are common, if all goes well this fish will be placed into a protected or CITES status w/in the upcoming yr. Forcing us (the hobbist) to pay more for the fish, or forgeting it. Eitherway is positive.
To answer your questions directly, a few times last yr people reported the same problem, they would get groups of banggai in and they all would drop. It might be the poor handling, or shipping of these fish, or harsh weather conditions,or that they orginiated from the same importer who treated them very poorly. I don't believe these fish are cyanide caught.
Sorry.
To read more on raising and breedin banggais:
http://www.eparc.com/banggai/banggai.shtml
frank