nterestingly enough there can be incomplete dominance between two genes or the switches which control two different colors. For example, a fish that is dominant or “on” for both of two different colors can be a combination of these two because they are both present. Think of this like mixing yellow and blue paint to get green! This being said let us consider a hypothetical mating between a red fish and a yellow fish. The red has the instructions for red coloring but the switch to make yellow is off. In the yellow fish the red switch is off but the yellow switch is on and causing yellow coloring.