Pterophyllum altum, also referred to as the altum angelfish, deep angelfish, or Orinoco angelfish,  occurs strictly in the Orinoco River Basin and the Upper Rio Negro watershed in Southern Venezuela, Southeastern Colombia and extreme Northern Brazil. 
The species is the largest member in its genus and specimens may have a height (from tip of dorsal to tip of anal fin) of as much as 38 cm (15 in).  Its natural base color is silver but with three brownish/red vertical stripes and red striations into the fins. The species may show red spotting and a blueish green dorsal overcast when mature and when aroused exhibits a black operculum spot. Characteristic of this species is an acute incision or notch above the nares (supraorbital indention). All true Orinoco altum specimens show this trait. The true wildcaught Orinoco altum is very difficult to breed in captivity. Most altum angelfish are more frequently found in the well oxygenated, extremely soft waters of Upper and Middle Orinoco tributaries shed from the Guiana Shield Highlands, preferring a pH range between 4.5 and 5.8. These are very transparent blackwaters with almost nil conductivity. Temperature range in these waters is between 78 and 84 °F (26 and 29 °C). They are also found in the Atabapo River and Inirida River floodplain, down the Casiquiare and Guainía floodplain where the Rio Negro is born, before entering Brazilian territory. Unlike P. scalare which prefer to spawn on the submerged leaves of plants and trees in the flooded rainforest, P. altum prefers to spawn on submerged roots and tree branches in a moderate water current. This species is recommended for intermediate to advanced aquarists due to the detailed maintenance it requires for proper health.
True Orinoco Altums are usually only available in aquarium shops from late summer until early winter due to the fact that their native river system's water level is only low enough to allow for successful fishing from July to October. 
Marine angelfish are perciform fish of the family Pomacanthidae. They are found on shallow reefs in the tropical Atlantic, Indian, and mostly western Pacific Oceans. The family contains seven genera and about 86 species. They should not be confused with the freshwater angelfish, tropical cichlids of the Amazon Basin.
The Rio Negro, or Guainía as it is known in its upper part, is the largest left tributary of the Amazon River, the largest blackwater river in the world, and one of the world's ten largest rivers by average discharge.
The cardinal tetra is a freshwater fish of the family Characidae of order Characiformes. It is native to the upper Orinoco and Negro Rivers in South America. Growing to about 3 cm (1.2 in) total length, the cardinal tetra has the striking iridescent blue line characteristic of the genus Paracheirodon laterally bisecting the fish, with the body below this line being vivid red in color, hence the name "cardinal tetra". The cardinal tetra's appearance is similar to that of the closely related neon tetra, with which it is often confused; the neon's red coloration extends only about halfway to the nose, and the neon's blue stripe is a less vibrant blue.
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 Basin, Orinoco Basin and various rivers in the Guiana Shield 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 transversely, 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.
The rummy-nose tetra is a species of tropical freshwater characin fish originating in South America, popular among fishkeepers as an aquarium fish. One of many small tetras belonging to the same genus, it is on average 5 cm (2 in) long when fully grown, and is a long established favourite among tropical fishkeepers. The fish is one of several very similar species including Hemigrammus bleheri, and Petitella georgiae, and it is possible that more recently collected specimens available in the aquarium trade are members of one or other of these similar species. The common name applied to most of these fishes is "rummy-nose tetra", though other common names are in circulation.
The flame angelfish is a marine angelfish of the family Pomacanthidae found in tropical waters of the Pacific Ocean. Other common names include flame angel, flaming angelfish and Japanese pygmy angelfish.
The gray angelfish, also written as grey angelfish and known in Jamaica as the pot cover, is a species of marine ray-finned fish belonging to the marine angelfish family, Pomacanthidae. It is found in the Western Atlantic Ocean.
Sorubim is a small genus of long-whiskered catfish native to tropical South America. A number of characteristics allows the differentiation of each species in the genus. Sorubim species are important food fish in South America and are highly significant to fisheries of some areas; however, harvests of these fish are not identified as much as other, more popular food fishes such as Colossoma, Arapaima, and Brachyplatystoma. Some species of this family are popular aquarium fish.
The flame tetra, also known as the red tetra or Rio tetra, is a small freshwater fish of the characin family Characidae. This tetra was first introduced as aquarium fish in 1920 by C. Bruening, Hamburg, Germany, and formally described in 1924 by Dr. George S. Myers. Today large numbers are bred in captivity and it is common in the aquarium trade, but the remaining wild population in Southeast Brazil is highly threatened.
Callichthys serralabium is a tropical freshwater fish belonging to the Callichthyinae sub-family of the family Callichthyidae.
Hypophthalmus is a genus of long-whiskered catfishes native to freshwater in tropical and subtropical South America.
Pseudolithoxus is a genus of suckermouth armored catfishes with five described species from the basins of the Orinoco, Casiquiare and upper Rio Negro in Venezuela. Additionally, a possibly undescribed species is known from the Trombetas and Nhamundá rivers in Brazil.
Cetopsis is a genus of catfishes of the family Cetopsidae.
The Atlantic spadefish is a species of marine fish belonging to the family Ephippidae. It is the symbol of the North Carolina Aquariums.
Paracentropyge multifasciata, the barred angelfish, banded pygmy-angelfish, many-banded angelfish, multi-banded angelfish or multibarred angelfish, is a species of marine ray-finned fish, a marine angelfish, belonging to the family Pomacanthidae. It is native to the Indo-Pacific.
Cephalopholis fulva, the coney or the butterfish, is a species of marine ray-finned fish, a grouper from the subfamily Epinephelinae which is in the family Serranidae which also includes the anthias and sea basses. It is found in the western Atlantic. It is associated with reefs and is a quarry species for commercial and recreational fisheries. It can be found in the aquarium trade.
Sternarchogiton nattereri is a species of weakly electric knifefish in the family Apteronotidae. It is native to the Amazon River system and feeds on sponges. Unlike other members of the genus Sternarchogiton, there is pronounced sexual dimorphism in S. nattereri, with reproductively mature males developing strong external teeth on tips of their jaws. These males are so different from the females and juveniles that they were thought to be a different genus and species, the "tooth-lip knifefish" Oedemognathus exodon, for over 40 years.
Synodontis nebulosus, known as the cloudy squeaker, or clouded squeaker, is a species of upside-down catfish that is native to the lower Zambezi River basin of Malawi, Mozambique, Zambia and Zimbabwe. It was first described by German naturalist and explorer Wilhelm Peters in 1852, from a specimen collected in the Zambezi River at Tete, Mozambique. The species name nebulosus is derived from the Latin word nebulosus, meaning "foggy", "cloudy", or "full of mist".
The harlequin sharkminnow is a freshwater cyprinid fish from central Africa. It is also known as the harlequin shark and variegated shark, especially in the aquarium hobby.
The Indonesian angelshark is a rare species of angelshark, family Squatinidae, known only from a few specimens collected from fish landing sites in southern Indonesia. It is thought to inhabit the deep waters of the continental slope. Reaching at least 1.34 m (4.4 ft) long, this species has a flattened, ray-like shape and a well-developed tail and caudal fin. It is characterized by the absences of fringes on its nasal barbels and thorns down the midline of its back, as well as by its relatively plain grayish-brown dorsal coloration with dark saddles beneath the dorsal fin bases and a black leading margin on the underside of the pectoral fins. The International Union for Conservation of Nature (IUCN) has classified it as Critically Endangered due to significant fishing pressure.