Fish were in abundance, from colourful reef fish to large open-ocean (pelagic) fish such as sharks and tuna. They would be grilled, fried, salted, or added to curries. The culture was rich with the knowledge of how to best make use of the environmental resources around them, even birds and crabs would occasionally be eaten.
Turtles were often caught and eaten, however the islanders respected the animal, they knew to allow females a chance to reproduce and never took more than was necessary.
Coconuts were not just used as copra or to make oil for exporting. Coconut palms were plentiful and used in a variety of different ways. The flesh of the coconuts themselves were used as food for families and their animals, the shells made ideal bowls, the tree trunks made boats and houses and the palm fronds were weaved together to make baskets or soaked in water to create alcoholic drinks!
For more information about history check Chagos: A History available from the Chagos Conservation Trust.