The interior dimensions of my cage are 42" Wide by 31" Deep by 64" High (44 cubic ft.). I have kept Gouldians for quite a while and feel ready to begin breeding them. I know I must maximize the population of Gouldian pairs to create as many mating choices as possible, but without overcrowding the cage. Can you tell me the optimum number of Gouldian pairs I should place in the cage to maximize breeding opportunities without overcrowding.