Last week I bought 2 beautiful blue rams that appeared to be healthy. yesterday one of them was lying dead on the bottom of the tank, and had lost a lot of colour.it looked like he had a kinda white slime covering him. this morning my remaining blue ram is lying close to the bottom of the tank and not moving around much. he looks ok, but when i put food in he didnt seem all that interested. i dont want to lose another fish, does anyone kno whats wrong?