Piabucus melanostoma

Piabucus melanostoma, sometimes called the chin tetra, is a species of freshwater ray-finned fish belonging to the family Iguanodectidae. This species is found in central South America. It is the second-largest species of the genus, but still only reaches about 12 cm (4 in) long. Occasionally found in captivity, it has an appealing iridescent-silver coloration. It is amongst the largest of fish still considered "tetras" in the aquarium hobby.