Ariari

The purple tetra, Hyphessobrycon metae, is a characid endemic to the middle Río Orinoco watershed in Colombia and Venezuela. Also known as 'Río Meta tetra', it is often misidentified, and H. peruvianus has repeatedly appeared under its name. The dark band on the caudal peduncle, without a broad dark band along the lower body, separates it from H. peruvianus and H. loretoensis.

The black spot piranha, Pygocentrus cariba, is restricted to the Río Orinoco basin in Colombia and Venezuela. Many of its habitats lie within the llanos, and it has been recorded from river channels, tributaries and floodplain lakes, many of them acidic blackwater environments. Specimens over 100 mm SL have a large humeral spot and few spots on the body, which separates it from P. nattereri. It is best maintained alone.