Unidentified Peruvian Characin?!

Hello,

I've recently come back from a trip to Peru and while in the Iquitos region of Peru I came across this little guy. I know its a Characidium sp. but I can't figure out the species. Any help would be greatly appreciated!

it looks like a goby

I am not well versed in freshwater gobies, but I don't think the fin structure on the pictured fish matches those of a goby. And this fish has a Characidium appearance.

But as to which species...there are more than 60 known species in this genus, with several having been described over the past few years. Fishbase lists 64 species, a few have photos but the majority do not.
http://www.fishbase.org/identification/SpeciesList.php?genus=Characidium

There is a short article about a few of the recently-described species on Seriously Fish:
https://www.seriouslyfish.com/tag/characidium/

This scientific paper might be of interest. "Species delimitation in Neotropical fishes of the genus Characidium (Teleostei, Characiformes)," Serrano, et al. (2018):
https://www.researchgate.net/public...the_genus_Characidium_Teleostei_Characiformes

There is also this guide which may have photos (I've not seen this book). It apparently lists 65 Characidium species.

Buckup, P. A., & Van der Sleen, P. (2017). Family Crenuchidae. In P.
Van der Sleen & J. S. Albert (Eds.), Field guide to the fishes of the
Amazon, Orinoco, and Guianas (pp. 142–148). Princeton: Princeton
University Press.

https://www.barnesandnoble.com/w/fi...co-and-guianas-peter-van-der-sleen/1126195859