Coral reefs are disappearing due to increasing ocean temperatures, water pollution, and acidification (caused by increasing carbon dioxide levels).

However, Parrot fish “can prevent algae from choking coral” because they “eat a wide variety of reef organisms” (cf Wikipedia). Down in Jamaica, unfortunately, as reported by ABC News,

parrotfish are now the most popular catch in heavily-overfished Jamaica, sold at the side of the road and in supermarkets and restaurants.

All hope may not be lost, though, because efforts are underway to seed coral reefs with fast-growing species. The trouble is, coral still grows very slowly, so we probably won’t really observe results of these efforts for many decades, if at all.