tom, once the embryo is sufficiently developed and eyes are clearly visible, can remain for many hours without water as long as they remain warm and moist. In the meantime you know that an established aquarium can go several days without a water change. That or just drain down to the eggs and change. If the tank is 30 inches high the top 3 inches is 10% of the of the volume. That brown fish is nothing but brown. Why is that? I was hoping that the black with red spots was somehow involved in this spawn. If someday that should happen I want them babies.