There are many cichlids, and other fish that have evolved long digestive tracts that allow them to process and eat overhanging leaves and fruits. As adults xCichlasoma pearsei and bocouti are mainly vegetarian, and many of Vieja types are fruit eaters in nature.
My bocourti will do serious damage to dandelions I pull from my yard.
before
after
Etroplus suratensus from India and Sri Lanka is also primarily vegetarian, I pull clumps of hair algae and hornwort from my pond that they eagerly chomp down.
In Mexico I watched these salt water fish grazing overhanging tree leaves.