Bigger, bossier familes more appealing for cichlid

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Seeking domestic bliss is a relatively low priority for some cichlids, with bigger and bossier families being more appealing, according to research to be published in an upcoming issue of the journal Biology Letters.

The study by Lyndon Jordan, Marian Wong and Sigal Balshine examined the group membership decisions of the daffodil cichlid (Neolamprologus pulcher).  

The daffodil cichlid is a group-living cichlid with subordinate individuals helping out the dominant breeding pair in taking care of the young.  

The dominance hierarchies in such groups are sized-based, and subordinate fish have to opportunity to inherit dominant status; however, subordinate fishes have been known to switch allegiances and move among groups.  

The authors examine group membership preferences in the daffodil cichlid to test the hypothesis that helpers prefer to join familiar groups when possible, but when faced with unfamiliar groups, choose based on the likelihood of improving their social position.

The experiments were carried out on eight groups of cichlids and 20 additional helper fishes obtained from other groups in the Zambian portion of Lake Tanganyika.  

The authors conducted a series of choice experiments in which the association preference of two focal helpers from each group for a familiar versus unfamiliar group, for familiar breeders versus familiar helpers, and for a group with small helpers versus one with large helpers.  

They found that the cichlids preferred to join familiar groups, but had no preference over joining groups containing only breeders or only helpers.  They also found that focal helpers joined groups with large helpers significantly more often than groups with small helpers.  

Although it may seem counter-intuitive to join groups where the social standing of the fish was worse and the fish were more likely to be bossed around, the authors hypothesized that the fishes joined the bigger and bossier groups because of the greater protection from predators afforded by the larger cichlids.

For more information, see the paper: Jordan. LA, MYL Wong and SS Balshine (2010) The effects of familiarity and social hierarchy on group membership decisions in a social fish. Biology Letters doi: 10.1098/rsbl.2009.0732.