At least when it comes to Fiji; there are no other major British colonies nearby to which they could have taken laborers. There are some smaller islands over in Kiribati, but they are not advantageous for plantation agriculture like the high islands of Fiji (Viti Levu & Vanua Levu).

When Fiji was annexed by the British, the importation of Indian labour around the empire had already been going on for sometime. More than 60,000 Indians were brought between 1879-1920 to work on the rapidly expanding sugar plantations in the colony. Indians were brought over to work in the fields since Fijians were not terribly keen to work on the plantations. Before the sugar boom in the late 1870's, Fiji had been home to a high lucrative cotton industry (they made out pretty well in the 1860s thanks to the US civil war); the early cotton plantations had attracted some Fijian labour, but a great deal of it came from other Pacific Islands where recruited signed islanders up for 3-5 year contracts to work on plantations on Fiji (Sydney & Noumea were other typical destinations). There was also a deal of "blackbirding" that took place; essentially kidnapping islanders and taking them to Fiji as forced laborers. The labour trade in Pacific Islanders was suspended in the 1880s because of the reports of blackbirding, kidnapping, and abuse; eventually it would come back under tighter regulation, but the cost/risk was always so great that government sanctioned trade in Indian labour was just a safer alternative.

I am not sure about Indian laborers being taken to Australia- but I suspect even if there was a limited population most of them would be been forced out with the advent of the White Australia policy, which forced out about 10,000 Pacific Islanders who had moved to the colony as laborers over the past four decades.