i have allway found the micros are allways jumpy and hate water changes ,esp when doing large changes ,i do think they get stressed , your asiatica is probably not bothered because it actually prefers the cooler water of the water change , i agree with downunder just try and be a bit gentaler with the changes , see if you can match the temp closer of the water you change , remember your micro is allready towards the lowest temp he will be comfortable at 24deg and if changing water with cold water this will drop the tank temp to below what he is comfortable with, hence he is getting stressed , maybe mix your water in a bucket at 24deg first then pour into tank . iam sure your micro will be ok as he is now at the size when they become much less fragile and can take a lot more than a juvie micro can
let us know how you get on
cheers col