Monocirrhus

The South American leaf fish, Monocirrhus polyacanthus, is a predator from Brazil, Peru, Venezuela, Colombia and Bolivia that mimics a dead leaf. It stalks prey head-down, appearing to drift like a leaf, and can swallow prey almost as big as itself. Flighty and very sensitive to deteriorating water quality, it is difficult to maintain and not a species for the beginner, and soft, acidic water is essential.