suphew, i had considered that so had checked before moving everything, there was no colour change or sign of stress, i also thought of the current from the return hose but the corner they were hideing in was were the return came out?, now after the change they are out in the open all the time and even if i walk up to the tank they dont dash off to hide, they will just swim around or swim upto the frount of the tank and look at me.