The trigger may also be something that is over looked, we know that they manned the collection of clowns over 6 inches in one of the regions they are still collected in. We also know that they are being hormone bread on farms both in the states and natural areas they are collected in. If they were to spawn during the wet season not only would the temp change drastically of the water but also the ph of the water would change. I'm not sure of the hormones that they use for breeding them on farms, but would it be possible to feed foods rich in the hormone needed to spawn the loaches. For example i know that shrimp is high in creatine that enhances the red - orange color in fish.