As parrotfish numbers dwindle, pollution and sedimentation might increase, an expert has warned.
The expert said fishing was to blame for the reducing numbers. He, however, said the fish were not likely to become extinct.
Parrotfish graze on reefs, eating seaweed that can crowd out the coral, outcompeting it for nutrients and space.
Coastal Oceans Research and Development - Indian Ocean East Africa director David Obura said if parrotfish numbers were low and algae more abundant, the additional fertilisation by pollution and sedimentation might compound the problem and reduce the amount of algae that parrotfish eat.
"Sediment on algae surfaces may make it difficult for some species to feed and pollutants in the sediment, on surfaces, in algae tissues may affect them," he said.
"Further impacts on parrotfish may arise due to climate change as ocean waters are warming, but we do not know much about which species are most vulnerable. As a herbivore, it is likely that parrotfish may be less vulnerable than other species."
His comments were in response to a number of posts circulating on social media asking Kenyans to stop catching parrotfish because their numbers were depleted, and algae levels were so high.
Dr Obura said a lot of focus had been placed on parrotfish in the Caribbean where there are fewer fish species and a disease killed off almost all grazing sea urchins in the 80s.
"As a result, parrotfish are the only major herbivores in the Caribbean, so their capture in fisheries leaves many reefs without any herbivores or grazers. With massive die-offs of corals due to global warming and other impacts since the 1990s, algae have taken over many reefs as it is not being kept in check by herbivores. So, in the Caribbean, countries have instituted major new controls and bans on parrotfish fishing," he said.
He said this dynamic is not the case in the Indian and Pacific oceans, nor in Kenya specifically, where there were many more herbivorous fish species, and urchins are abundant.
"Of course, fishing them down too much is a problem, but this is the same for all fishery resources," he said, adding that a ban on parrotfish fishing will do a lot of damage to already difficult fishery conditions.
"Parrotfish are extremely important, but so are many parts of a reef,"said Dr Obura.