In CA/SA, there are many sucker mouth plecos and live bearers that eat algae. In Asia, there are sucker mouth Gara, flying fox, CAE and SAE that eat algae. In Africa, there are no sucker mouth algae eaters available in the hobby or in existence I’m aware of. Mbuna, Tropheus, some catfish and Tilapia assume the role of algae grazer in Africa, but in domestication, they get lazy and eat only fish food.