Angel fish

Contrary to popular belief, this species of fish is actually a freshwater species, spending little time in brackish water before swimming back to their freshwater biotope. However, fish of the same species have been found in coastal sea waters, brackish swamps and freshwater streams, living and breeding. 
Pterophyllum is a small genus of freshwater fish from the family Cichlidae known to most aquarists as "angelfish". All Pterophyllum species originate from the Amazon River, Orinoco River and Essequibo River basins in tropical South America. The three species of Pterophyllum are unusually shaped for cichlids being greatly laterally compressed, with round bodies and elongated triangular dorsal and anal fins. 
This body shape allows them to hide among roots and plants, often on a vertical surface. Naturally occurring angelfish are frequently striped longitudinally, colouration which provides additional camouflage. Angelfish are ambush predators and prey on small fish and macroinvertebrates. All Pterophyllum species form monogamous pairs. Eggs are generally laid on a submerged log or a flattened leaf. As is the case for other cichlids, brood care is highly developed.