I had two Bettas, a killifish, and a red tetra died when I got home last night. My water was cloudy with all these floating particulates in the water. All the other fish was losing color and going to the surface for air. I did a 75% water change and the fish are back at full color and active again. I was gone the entire day and got home late at around 11. I feel terrible that my male killifish died.