Egg-spots on Astatotilapia burtoni.​

We've all seen egg-spots on mouth-brooding cichlids, particularly on male haplochromines. The assumption has always been that the egg-spots spur the female cichlid to "pick up" the eggs and as a result, fertilize the eggs in her mouth. However a new study has found that egg-spots play less of a role in courtship and reproduction than thought. For instance, males with no egg-spots produce just as many fry as males with many egg-spots. Females appear to not need to be tricked into picking up the fake eggs for fertilization to occur. Also, females seem to show no preference in the amount of egg-spots in males. The one place where egg-spots do matter seems to be between males. Males with fewer egg-spots are often the target of aggression by males with more egg-spots. The question seems to be, why are egg-spots even there? Details of the study can be found on PLOS ONE.