The Princess of Lake Tanganyika (Neolamprologus pulcher), a cichlid fish which is popular in home aquariums, are cooperatively breeding fish with a dominant breeding pair and several 'helper' fish that do not normally breed but instead assist with raising offspring. Helpers also play a crucial role in defending the group's territory against outsiders - although helpers also compete with the breeders for resources and reproductive opportunities. The researchers, led by Dr Markus Zӧttl of the University of Cambridge, wanted to find out how environmental pressures might influence the acceptance of new immigrants. He said: "All animal societies are affected in one or another by immigration and when we seek to understand social organisation we need to understand which environmental factors influence processes like immigration."

The full story on Neolamprologus pulcher/brichardi breeding habits Environmental factors determine whether immigrants are accepted by cooperatively breeding animals.

Environmental factors

Neolamprologus pulcher. Photo by Guérin Nicolas​