Water quality is the most important factor influencing the health of eggs and fry. Before the eggs are placed in the incubator, chlorine (if present) must be removed from the water. This can be accomplished in one of two ways: 1. Let the water sit in the tank or bucket (with the lid off) for 72 hours while the chlorine naturally dissipates, or 2. Add a chlorine-removing agent to the water. This chemical can be obtained at most aquarium supply stores. The bottom line - chlorine will kill the eggs of salmon and trout.
Salmon and Trout are cold water fish. Water temperature is especially crucial during the incubation process. For the eggs, the water temperature should be within 3 to 4 degrees Fahrenheit of the temperature at which the eggs were kept in the hatchery (colder is better than warmer). Later, as the young fish mature, the temperature may be gradually elevated - but usually not much above 55 degrees. Water temperature is discussed in greater detail elsewhere.