I would not recommend eating the local reef fish unless you are able to speak with a local fisherman. Ciguatera seems to be common in fish in certain locations, but not others, and the local fisherman know this.

Deep water fish (mahi, wahoo, tuna) that you may catch trolling out to Anegada are perfectly fine to eat

If you do plan on fishing be certain to apply for a BVI Fishing License as well ahead of your trip!