Fish turn white then back?

if its just when your doing something with the tank like with the lid off or turning the light on the fish may turn pale because it is a bit of a shock since in the wild the sunlight doesnt normally just switch on its a bit unnatural. my clown loach dont like it when im messing around in the tank or turn the lights on they go really pale too but soon get their colour back when ive done. they will most likely just be shocked and scared one of mine got that scared once they jumped out onto the carpet luckily i put him straight back in and he was fine. i wouldnt be too worried about it im sure they will be fine. the only other thing that turns some fish pale is if the water quality isnt very good then they go pale hope this info helps :)