The Orinoco is one of the longest rivers in South America at 2,250 kilometres (1,400 mi). Its drainage basin, sometimes known as the Orinoquia, covers 880,000 km2 (340,000 sq mi), with 76.3 percent of it in Venezuela and the remainder in Colombia. It is the fourth largest river in the world by discharge volume of water. The Orinoco River and its tributaries are the major transportation system for eastern and interior Venezuela and the Llanos of Colombia. The environment and wildlife in the Orinoco's basin are extremely diverse.
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.
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 red garra, also known as the doctor fish or nibble fish, is a species of cyprinid that is native to a wide range of freshwater habitats in subtropical parts of Western Asia. This small fish typically is up to about 14 cm (5.5 in) in total length, but locally individuals can reach as much as 24 cm (9.5 in).
Hemichromis is a genus of fishes from the cichlid family, known in the aquarium trade as jewel cichlids. Jewel cichlids are native to Africa. Within West Africa, Hemichromis species are found in creeks, streams, rivers and lakes with a variety of water qualities including brackish water lagoons.
Geophagus is a genus of cichlids that mainly live in South America as far south as Argentina and Uruguay, but a single species, G. crassilabris is from Panama. They are found in a wide range of freshwater habitats. They are part of a group popularly known as eartheaters and mostly feed by picking up mouthfuls of sediment to sift out food items such as invertebrates, plant material and detritus. The largest species reach up to 28 cm (11 in) in standard length. They are often kept in aquariums.
Heros is a genus of cichlids native to the Amazon, Orinoco and Essequibo River basins in South America. They were previously included in the genus Cichlasoma before its restriction to the distinct group of "Port Cichlids."
Hypselecara is a small genus of cichlids native to the Amazon and Orinoco basins in South America. H. temporalis is a relatively common aquarium fish known in the aquarium trade as the chocolate cichild.
The threadfin acara, also known as Heckel's thread-finned acara, is a South American species of cichlid fish. It is the only member of the genus Acarichthys and is native to rivers in the Amazon and Essequibo basins in tropical South America, and has become established in southeastern Asia. It is sometimes found in the aquarium trade.
Heros severus, is a species of tropical freshwater cichlid native to the upper Orinoco and upper Rio Negro basins in South America. It has historically been confused with several other species in the genus, most recently H. liberifer.
Satanoperca is a small genus of cichlids from South America, where they are known from the Orinoco, Essequibo, Nickerie, Amazon and Paraná–Paraguay river basins. They are mainly found in areas with slow-moving waters, but some species have also been recorded from rapids.
Hypancistrus is a genus of loricariid catfish originating from the Amazon basin in South America. Unlike many of the other Loricariids, however, some Hypancistrus species are more carnivorous and enjoy meat in their diet. Hypancistrus species are popular aquarium fish, including such popular fish as the zebra pleco and Queen Arabesque pleco.
Laetacara is a small genus of cichlids native to freshwater habitats in tropical and subtropical South America, ranging from the upper Orinoco River basin in Venezuela to the Paraná River basin Argentina. The genus is also collectively known as the smiling acaras. Like all cichlids, Laetacara species have well-developed brood care.
Mesonauta, the flag cichlids, is a small genus of cichlids native to the Amazon, Orinoco, Essequibo, Paraná and Paraguay basins in South America. Mesonauta is included in the subfamily Cichlasomatinae. They occur in various freshwater habitats such as streams and lakes, especially in areas with little water movement and aquatic vegetation. They are generally found in small groups that stay near the water surface. To avoid predators, adults may jump out of the water and juveniles mimic leaves.
Peckoltia is a genus of small South American armored suckermouth catfishes. Many of these fish are popular aquarium fish.
The African jewelfish, also known as jewel cichlid or jewelfish, is from the family Cichlidae.
Heros efasciatus is a species of tropical freshwater cichlid native to the Amazon basin in South America. It is commonly found in the aquarium trade, often in its gold colored variation rather than the wild-type olive green one.
Nannostomus anduzei is a freshwater species of fish belonging to the genus Nannostomus in the characin family Lebiasinidae. It is native to Venezuela and northern Brazil, particularly the upper Orinoco and Rio Ererê, a tributary of the Rio Negro. The adults grow to a maximum length of only 16 mm, making them one of the smallest pencilfish. Other common names include miniature pencilfish, miniature nannostomus, and Anduzi's nannostomus.
Heros notatus is a species of tropical freshwater cichlid native to Rio Negro and Essequibo River in South America.
The saddle cichlid is a species of cichlid from the tribe Cichlasomatini, part of the subfamily Cichlasomatinae from South America. It is the type species of the genus Aequidens. It is reasonably common in the aquarium trade.
