There are 400 or more types of plants, fruits and vegetables that can be grown in a high quality aquaponics system. A large number of them are highly nutrious such as tomatoes, lettuce, bananas, etc
We can also nurture a variety of fish that we can eat from although we can simply fish our own fish from the ocean
In terms of meat, we can use plants grown on aquaponics to feed animals or we can import our meat to start with.
In terms of cereals yes it's limited we can always import those or find other solutions or adjust our diet accordingly.
What's more important is we can sustain ourselves 100% with just aquaponics, fish (farmed or wild) and limited animals. The rest can be imported, There is so much potential in this field for Bitcoin island sustainability.
Aquaponics can also be used to create our own biofuels, just see where this can go.
As for drinking water, we can use desalination powered by solar energy, that solves part of the problem but the cost of desal is still high.