If you have a
Mormon Family History Centre near you, you can order in a copy of the microfilm of European Deaths in Fiji. It should be one of these, depending on when you think he died.
General deaths 1880-1888 - FHL INTL Film [ 763604 ]
General deaths 1871-1879, 1889-1891, 1894 - FHL INTL Film [ 763605 ]
General deaths 1896, 1899-1900 - FHL INTL Film [ 763606 ]
These films are photographed copies of the registration books, so you can print out the actual entry, once you find it.
His death could also be mentioned in the Fiji Times. Try the large libraries in
Sydney, to find one that holds it on microfilm