My new platy is staying on the gravel

I bought new fish and shrimp today including platys. One of my new platy is just sitting on the gravel not moving but all the other fish are fine. The fish shop checked the water which was fine so I don't know what it could be. Is it stress of being moved to a new tank? It can't be from over feeding either as I haven't fed them as the fish shop did and I'm sure they wouldn't over feed them.

Hi and welcome to the forum

The fish is probably stressed from the move. Make sure you have some floating plants in the tank and a picture on the back of the aquarium to help them feel secure. You can turn the tank lights out for today but leave the curtains or room light on so they can see where they are.

In the morning open the curtains or turn the room light on at least 30 minutes (or more) before turning the tank light on. This will reduce the stress on the fish and they won't go from a dark tank to a bright tank instantly.

At night turn the room light on and then turn the tank light off. Wait at least 30 minutes (or more) before turning the room light out. This allows the fish to settle down for the night instead of going from a brightly lit tank to complete darkness instantly.

Thank you, I will try this and hopefully they'll feel safer