Platinum Argus, I know a breeder and exporter from China who said the biggest he has seen is 23 inches. But I'm sure it should get bigger than that.
I wonder if this is just an albino Argus or a variety of Argus species. If it is just an albino it should get pretty big as Channa Argus gets to about 3 feet if not more.
Platinum is a leucistic morph of c. argus . They will get just as big as regular argus, rare to find big ones on English sites since like most monsters people don't/can't keep them into adult size but if you search for them using there Chinese names you'll find plenty of examples of monstrous sized platinums.