Piabucus melanostoma

Piabucus melanostoma, sometimes called the chin tetra, is a small species of freshwater fish from the rivers of 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.

While it is commonly referred to as P. melanostoma, it is also easily found under the name P. melanostomus. Its baisonym is P. melanostoma, and it is more often listed as such, but both are used by the scientific community.