Definitely not a syno or pim as it has 8 barbels (an extra pair of nasal barbels that pims and synos don't have), but, as Wills says, Mystus is a good possibility. I also don't think it's M.cavasius - if it was it would have the dark spot behind the gills, which your fish doesn't.
For me, the eyes look just too big for a Mystus but that's not saying it's isn't one.
Martin