I hate to tell you, but two days is not enough. Your tank is not completely cycled.
Between that and the uneaten food, the tank is set to fail.
My advice, since you already have the fish, buy some Stability, follow the directions to the t and stop feeding altogether for a day or so. Water clarity usually means your filter is not yet cycled or overfeeding, or in your case, both. If you can do all this in the 40 youll be much better off. Good luck!