Graeme, I would try our 'small foods mix' which consists of (well defrosted) frozen daphnia, baby brineshrimp, and cyclops. Ours have been eating plenty of this and are definitely putting on weight. They do seem to cope fine with Levamisole treatments too, so you should be ok to go ahead and worm them. The trouble with taking home skinny delicate fish like these so early is that you run the risk of not being able to feed them as intensively as may be needed without causing problems in the aquarium. That's why I prefer to fatten up specimens like this with lots of feeds per day on a system that can take several large water changes each day before I will consider selling them.
Over the last few weeks I have seen numerous fish lists with both
H. confuzona and
H. orthogoniata on them, so either both are being exported at the moment, or the suppliers are guessing at IDs.
Good luck with them!
Emma