Salmon/Trout eggs are generally delivered to the school in January. The number of eggs delivered depends on the size of the aquarium. The rule of thumb is ten eggs per gallon of water. The eggs are called "eyed" because of the two dark spots evident within the developing embryo. These are the actual eyes of the fish. The eggs have been incubating at the hatchery for approximately three months and have reached a stage in their development where they can tolerate handling relatively well. Use of eyed eggs improves salmon family survivability in the classroom.
Placing the eggs into the incubator is a relatively simple endeavor. Water temperatures in tank and delivery container should be about equal - within 3 to 4 degrees Fahrenheit (colder is better). Using a small dip net or slotted spoon, carefully scatter the eggs over the surface of the gravel. The eggs should be placed where students can see them through the viewing window. Eggs resting on top of one another are not a problem. This is what occurs in a natural redd.