When you say face down, do you mean that he is vertical or that he is swimming on his back?
If its either then its probably a swim bladder problem, this can be caused by many things among them poor water quality and over feeding leading to constipation. Try giving a garden pea (shelled) and crumble over the surface of your tank, greens can help prevent constipation. If that fails go to your local pet shop (preferably one that is solely for fish or that has a good fish section) and get your water tested to make sure that the quality is fine, a swim bladder treatment along with some aquarium salt.
The salt will help to balance electrolytes and promote gill function, this helps the fish feel better and helps them get better. Be sure to watch the amount your feeding your fish they can be easily over fed, if your feeding once a day then the amount they will eat in 2mins is a good amount. They will also need meat protein as well as vegetable so if your giving treats such as bloodworm then always make sure there is vegetable protein as well, live plants are good for this and they also help to oxygenate your tank.
While your at the pet shop find out if your tank is big enough for your fish, you didn't mention how big your tank is or how long you have had it, so it might be a good idea to find out if you need to upgrade your tank.
Hope this helps.
If its either then its probably a swim bladder problem, this can be caused by many things among them poor water quality and over feeding leading to constipation. Try giving a garden pea (shelled) and crumble over the surface of your tank, greens can help prevent constipation. If that fails go to your local pet shop (preferably one that is solely for fish or that has a good fish section) and get your water tested to make sure that the quality is fine, a swim bladder treatment along with some aquarium salt.
The salt will help to balance electrolytes and promote gill function, this helps the fish feel better and helps them get better. Be sure to watch the amount your feeding your fish they can be easily over fed, if your feeding once a day then the amount they will eat in 2mins is a good amount. They will also need meat protein as well as vegetable so if your giving treats such as bloodworm then always make sure there is vegetable protein as well, live plants are good for this and they also help to oxygenate your tank.
While your at the pet shop find out if your tank is big enough for your fish, you didn't mention how big your tank is or how long you have had it, so it might be a good idea to find out if you need to upgrade your tank.
Hope this helps.