As mentioned they are only collected by one guy on Cocos. This was a condition of sale when the Clunies-Ross family sold the Island to the Australian government.
Monopoly at its greatest.
About 7 years ago I paid a lot of money to the then regulatory body AFMA (Australian Fisheries Management Authority) to determine the feasibility in allowing a permit to be issued to collect this species from Christmas Island (where they are far more common).
The study over 12 months proved that it was easily sustainable and that a licence application would be supported if I applied.
I subsequently did, the management authority was suddenly changed to Western Australian fisheries, and it was then rejected!
Not conducive to supporting the local economy. *** is that about. I live in the state?
I was dirty.
I've subsequently found out there was a bit of "ahem" political pressure to preserve the existing monopoly.
Anyway enough of my rant.
They are hardy fish, always found deeper than 20m, and are nearly always in harems. (At least in my 30 dives on Christmas Island)
I caught a couple, and they were eating brine within 30 minutes of surfacing whilst still in buckets.