Mbuna capable of sex reversal, says study


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Sex reversal in the shell-dwelling Lake Malawi cichlid Maylandia cf.

livingstonii has been documented for the first time in a paper published in the most recent issue of the journal Copeia.

Jay Stauffer and Renea Ruffing conducted a series of experiments to show that this species is capable of changing sex.

In the first set of experiments, the authors used tanks divided into two compartments by a sheet of clear Plexiglass, where they placed one male in one compartment and three females in another.

In the second set of experiments, the authors maintained six females in two tanks and seven females in another two tanks, all in the absence of any male fishes.

In the first set of experiments, one female developed male secondary characteristics usually seen only in dominant males, and then fertilized eggs produced by one of the remaining females in the experiment, resulting in three large broods of fry.

In the second set of experiments, one female each in the tanks that held six fish began to display male coloration and behaviour after two months. During the third month, a female in one of the tanks was observed to be holding eggs, releasing a brood of fry two weeks later.

The authors note that although their experiments showed sex reversal, further studies are needed to document whether sex reversal occurs in the wild.

For more information, see the paper: Stauffer, JR Jr and RA Ruffing (2008) Behaviorally induced sex reversal of Metriaclima cf. livingstoni (Cichlidae) from Lake Malawi. Copeia 2008, pp. 618"620.

Nomenclatural note: although the issue of whether the correct generic name to be used for this species should be Metriaclima or Maylandia remains contentious, strong evidence has been presented that the latter name is the correct one to use. We follow current databases (e.g. Catalog of Fishes) in using Maylandia.