I think that there are a lot of variables that could be at play, especially today. According to the member from Indo that I was in contact with years ago when I posted the Kalimantan vs Sumatra sticky, many of the loaches collected in the wild during the rainy season, are kept in holding ponds until much later when they are much larger, and fetching much higher prices in the off season. That, and according to others there are now a number of domestic breeders, using hormones and also growing out in ponds, in Asia, the Czech Republic, and no doubt elsewhere. If there is a $ to be made, someone will be making it. So today not all imported loaches are necessarily wild caught, so worms etc may not be as much of an issue, as in the past. Also, those grown out in ponds may be getting prophylactic treatment long before being exported. Not sure which thread it was in, possibly the export study thread I posted some LFS pics of captive F1 clown loaches, that came from Florida years ago. Most died before they were sold, very small loaches, tiny, and apparently too fragile for the care given by employees at the local Petland.