These brilliant blue and green fish are pretty easy to spot as you swim along the reef. You will see these colorful fish grazing along the reef and eating the algae along with some of the dead corals. Listen out underwater and you might just hear the distinctive crunch of some types of parrotfish as they chew on coral. It takes tough teeth to take on a stony calcium-carbonate diet. Their incredible teeth are fused as one to their jawbone. The crystalline structure of their teeth is so sturdy, it would beat gold, copper and silver in a fracture test. Parrotfish are somewhat dangerous to consume, due to the high prevalence of ciguatera, which is a toxin that comes from eating the algae on the reefs.
Parrotfish spend up to 90 percent of their day eating algae and dead coral, effectively cleaning up the ocean and helping our reefs to thrive. They also poop out fine white sand that ultimately line our shores. It’s estimated a single parrotfish could produce anywhere from 200 up to 1000 pounds of sand each year, depending on the size and specie. Parrotfish literally turn toxic, reef-killing algae into beautiful beaches! The reefs that will not be able to survive without this beautiful algae-eating filter fish.
Before they go to sleep each night, some species of parrotfish build a transparent cocoon made of mucus secreted from special glands in their gills. It not only keeps them safe from parasitic isopods that attach while the fish sleep, but may also mask their smell from night-time predators like moray eels and sharks.
Parrotfish change their sex throughout their lives, swapping from female to male as they grow. One big brightly colored male will defend a harem of smaller, duller females. But as they grow bigger, females will often change sex and then challenge other males to lead the group. It’s a process known as “protogynous hermaphroditism” and each time they do it, their color changes drastically too.