what's up with the dead mouse in the water? I'm sure you wouldn't leave it in there long, but don't you think that would foul your water quick?
I just noticed all the pellets too, that's going to foul your water quick too if the lap isn't used to eating them.
Best thing right now would be chopped up shrimp and a clean tank. Dim the lights, and add more plants and hiding spots to help it feel comfortable. You can make it more open later when it's health is back.