Bryconops piracolina reaches a maximum of roughly 7.1cm (2.8 in) in standard length (excluding the tail fin).

[3] Its dorsal fin sports pigmentation along the base that streaks away from the body, which is a unique feature that can be used to distinguish it from its congeners.

When a specimen is preserved in alcohol, the scattered black chromatophores (pigment cells) on its face, head, and upper jaw become more evident, though they have little impact on overall coloration.

[5] Its lateral line also becomes much clearer, manifesting as a bold, dark stripe against scales that turn a yellowish-brown.

[17] The Piracolina and its tributaries are surrounded by cultivated farmland, largely soy and corn, with very little riparian vegetation.