I bought 2 Angelfish and 6 Black Skirt Tetra's a week ago, to add to my established tank, which already contained 2 Black Skirt Tetras that I've had for awhile (the only fish in the tank). The Angelfish were really small and the Tetras somewhat larger. I just got them into my 20 gallon tank and one of the Tetras ate one of the Angelfish. I went back to the store and they replaced it with a bit larger Angelfish. A few days later, one of the Tetras ate the other small Angelfish. The larger Angelfish (size of a quarter maybe) was cowering in the tank, behind the heater. I quickly set up a 5 gallon tank for the remaining Angelfish, using substrate and a carbon filter medium from my 20 gallon tank, but the air filtration system won't work. Will my Angelfish live in still water until tomorrow?