Mastacembelus dayi
Looks just like the one I picked up.. 12-20inches is what I've seen. the 12" is based on 3 specimens collected.. but they've been imported for the pet-trade as large as 20" supposidly. I'de say realistically 12"+ so a 75 should be adequite or a 125. My guy is still very reclusive. seems to be as boisterous as a TT though, I've already had to block off the HoB as he went up into my filter the night I got it.
Judgeing from the head size/body. I'm inclined to believe they get respectably size. their not as "petite" looking as a peacocks or zig zags head imo.