arapaima gigas the giant freshwater fish of the amazon and essequibo basins a profile of the majestic pirarucu

arapaima essequibo south america scaleless catfish arapaimidae pirarucu brazil colombia peru bolivia food endangered bony tongue giant amazon basin migratory schooling solitary adult size maximum length water acidity alkalinity turbidity spawning reproduction breeding parent body shape conservation status threatened biodiversity web sustainable fishing cultural significance patterns habits top predator river waterways