I really did not why it died. Perhaps it was to do with the water or pressure. Got it from a LFS. I have it lucky coz we have a few well stocked LFS that I visit on a regular basis, and sometimes they do have very nice suprises. It's quite common to come across octopus here but none of the shop owner really have any clue what species they are.
I have never kept Nautilus, but see plenty of recently imported specimens. I'm working towards a custom built set up, In the mean time I'm finding as much info as I can.
Nautilus seem to be able to tolerate low water pressure, although captive hatched specimens survive less than a year, possibly due to lack of pressure. Obviously a deep tank to allow some vertical migration would be a benefit.
The biggest problem in my opinion with keeping a Nautilus is temperature. They normally occur in deep water, around 300m, and rarely come up above 100m This means although the areas they come are tropical the water is very cold. I know when specimens were collected for Waikiki aquarium they shipped them at close to freezing!
I often see Nautilus at a supplier I visit, as they are kept in tropical conditions they look unhappy. But occasionally the odd one seems to be OK. A healthy specimens will often have it's tenticles extended and can be quite active. See picture. If the Nautilus has it's hood permantly down, this is a bad sign.
Feeding a healthy Nautilus should not be a problem, the are primarily scavengers and should take dead prawns.
Hope this helps potential keepers.
i've never kept a Nautilus myself, but some years ago I worked for an aquarium in southern florida where we had a deep benthic exhibit including Nautilus for a while.
you are absolutely correct about the pressure. the aquarium had set up a very special tank with considerable amount of donor money. the tank provided several atomspheres of pressure and contained an airlock for feeding. unfortunately they had to keep it undecorated since cleaning was troublesome.
i realize that's a bit extreme for a normal person's home, but just thought i'd share.