I had 2 more fish die. I check my water and everything is fine. should I do another water change. even though my water is fine? I had one dead glo fish and one eyed tetra die in my 20 gallon tank. My tank is cycled. I did a water change a few days ago. I did a liquid test on my tank and everything is fine. No Ammonia, no Nitrite, is in the tank, there is 5.0 Nitrate.