do you have a lot of hiding places for your fish? like decor, plants, etc. usually the more places they can hide or retreat to, the safer your fish will feel. other than that, does it look sick and does it eat regularly.
try throwing in a few silk plants (if your using fake plants) if it looks fine. one of my female tetras constantly hides because of harassment from males, but otherwise it is healthy. i'll probably need to get more females to balance it out.