When I do my tub maintenance, thats about the only time I handle my balls....*lol snickers*. So I can read there body language pretty good. If there just balled up laying there I will just reach in and remove them to the holding tank. But if I lift up there hide and they coil back I know there none to happy so I will give a little spray from my water bottle to change the insuing outcome and I gently pick them up and there good to go.
I've never had one strike or show any aggression once I have them out of there tub. My biggest girl is 750 grams as of right now and range all the way down to 250 grams.