Animal Quiz: The Heaviest The animals in this quiz bring quite a lot pounds on the bathroom scale. Not just predators, but also birds and fish. Do you know the correct answers? Animal Records Quiz: Heaviest Animals Which of these primates is the heaviest? Which of these fish is the heaviest? Which of these animals is the heaviest? Which of these predators is the heaviest? One of these birds weighs almost 44 lb (20 kg), but can still fly. Which one is it? Which of these reptiles is the heaviest?