The Fish of the Great Barrier Reef. Have you ever wondered how the Great Barrier Reef Marine Park protects the incredible fish diversity on the Great Barrier Reef? Zoning is key. By creating different zones with specific rules, they ensure fish have safe havens to thrive. Some areas are off-limits to fishing, giving fish populations a chance to flourish, and some zones have limited fishing to help maintain a healthy ecosystem. Ask the Master Reef Guide what zone you are in next time you visit. �