The site where the picture is linked from calls it "san1 xian3 yu2" -- three line fish, but I think that's just a direct Chinese translation of "trilineatus", not the local name of the fish. Maybe the document I sent you (which was in turn sent to me by Hok Hee) may mention this fish.
I'm sure there must be a colloquial Chinese name for it. The name you cite -- sanxian nichang -- is simply a direct translation of Psuedobagrus trilineatus and appears to be the Chinese formal name ("ni" of course meaning "pseudo").
I don't think there's a colloquial Chinese name for the fish. In Chu et al., most of the other Chinese bagrids have colloquial names listed, but not this species.
Checking two other Chinese references (珠江鱼类志 and 广东淡水鱼类志) reveals the same formal name being used.
I think that there probably isn't one, since the fish was discovered fairly recently (1979).