Super Cichlid Sisters

Many types of fish turn to shoaling to avoid ending up as a meal, but the details about who shoals with whom differs from species to species. Examining shoaling behaviour can thus reveal a lot about a species, and scientists examining the rocky Zambian coastal waters of Lake Tanganyika were intrigued to discover that some of the Cichlids there used shoaling to turn “normal” gender roles upside-down.

Amongst the great majority of creatures and particularly mammals, it is normally the males of the species that stray furthest from home in order to avoid inbreeding and competition for resources. Meanwhile, the females stay closer to the home or nesting area. However, the scientists discovered that female Caudopunctatus Cichlids (Neolamprologus caudopunctatus) were dispersing up to eleven times further away from their nesting grounds than their male counterparts.

Although scientists haven’t yet explained the reasons behind this behaviour, they did note that the females were being decidedly clever about it. Smaller, younger females tended to shoal with their older, larger female siblings and this tactic is effective both in mitigating the risks of being further away from the safety of home, and in maximising the chance of at least one member of the family surviving. By relying on “sister power” in this way then, the female cichlids help ensure the continuation and spread of their genetic information and thus the continued survival of the species.