Moenkhausia costae was described by Steindachner in 1907, as Tetragonopterus costae, and it was at the beginning of the present century that ichthyologists agreed it is actually in the genus Moenkhausia. For whatever reason, it has not been seen all that much. There is no record of the species on Seriously Fish. However, I am quite familiar with two other species assigned to this genus, having kept and spawned Moenkhausis pittieri ("Diamond" Tetra) and M. sanctaefilomenia (various common names). Both can get a tad nippy, though not to the extent of fish like the Tiger Barb, but it is worth the caution.
This is one of the advantages of using the scientific name. Species in the same genus are much more likely to share a number of common traits and behaviours. I would consider this species to be much like Silvertips in this regard, so beware.
I just spotted bloodfins mentioned earlier...the species in this genus, Aphyocharax, are notorious for fin nipping. One of them, A. paraguayensis, not a "bloodfin" but a species in the same genus, is one of the most aggressive very small fish in the hobby. I once added a group of 15 to a heavily planted 90g tank and within two days of adding them, every other fish in the tank was quivering behind the plants and would not even come out to feed. The A. paraguayensis quickly came out of this tank believe me; I don't tolerate any fish terrorizing the other inhabitants in an aquarium. None of the "bloodfins" are good community fish.