Bryconops tocantinensis reaches about 6.5 cm (2.6 in) in standard length (excluding the tail fin),[1] which makes it one of the smaller members of the genus.

[1][5] Bryconops tocantinensis demonstrates sexual dimorphism in that mature males sport bony hooks on the rays of the anal and pelvic fins.

Since its description in 2016, B. tocantinensis has been considered a member of the subgenus Bryconops due to the lack of teeth on its maxillaries.

[6][9] The presence of riparian vegetation in its natural habitat offers the possibility that it eats insects that fall into the water from trees overhead, as is seen in congeners B. inpai and B.

[1] Nonetheless, the Tocantins basin at large is under anthropogenic threat, which may place it under greater survival pressure.

[12][13] Deforestation and logging are also among the current means of habitat destruction, which has a significantly negative impact on the riparian zone.