I am saying fasciatum, I have kept only tigrinum, and they had a more pronounced snout. The snout in fasciatum is more diminutive. Other than that it's hard to tell till he's a lil bigger, and his true patter emerges. here's a pic of a tigrinum I kept that was killed by a pacu bite to the cranium!
From the shorter snout I would guess that it is a young fasciatum, here is a comparison pic of one by Landines.
Here is also a pic of a young tigrinum by Johnny Jensen.
the fasciatum is the top one.