Neither species was able to make a dent in the damaging algae. Nor did any of the remaining 41 herbivorous fish found in the area make much of a difference. Instead, the researchers found that a rare batfish, Platax pinnatus, moved in. The team was surprised to see the batfish act this way, as they usually feed on plankton and invertebrates on the sea bed. “In five days the batfish had halved the amount of weed. In eight weeks it was completely gone and the coral was free to grow unhindered,”
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Batfish are vulnerable because of their large size, which makes them attractive to spear fishers, and because their young depend on coastal mangroves which are in decline in many areas. For now, they are one of the last populations apparently capable of reversing the fate of coral reefs that have been damaged by overfishing. Already, the reef has all but lost two major weed-mowers: dugongs and green turtles.