As it is Finals Season I haven't had time to do my weekly water change this weekend. All the parameters in my tank are normal except my pH, which is a little higher than normal. No fish have been added to the tank in 3 months, and it is understocked. One of my neons has been swimming around with his mouth stuck open as though he's not getting enough oxygen. His color is also pale. All the other fish are acting normal and appear healthy. There is an abnormal green slime floating on the surface that sticks to my skin when I put my arms in the water. Is there something wrong here that I can't recognize, or is this little fish just meeting a premature end?