From reading, it sounds true. Clarias batrachus is by far and large the main player. I've seen Ben (aka Amiidae, the owner of PFK - Predatory Fish Keepers forum) obtain a lot of the small walking cats of other genus or species and post them for ID on PCF. You can ask him. Or surely can ask Neil from Pier Aquatics.
You are not close to either, I understand, but Pier ships, I think, and Ben who lives in Singapore knows lots of in and outs. Guys from ScotCat should be helpful too.