Cobalt Zebra Brooding?

Question
I have a Cobalt Zebra (Maylandia callainos - 99% sure), which I originally assumed was a male.  We had it in our main 55gal tank, with a Kenyi and 2 Electric Yellow labs (not even sure these are all compatible, which may have been the root of the issue).  The cobalt got quite aggressive towards the Kenyi, to the point where I had to remove it (cobalt) to its own tank. Now the confusion begins.  This fish is a very energetic digger, which I thought was a male trait.  However, it has stopped eating, and keeps doing this yawning/stretching/shifting thing with its mouth, which to me looks like it may be aerating eggs.  I have bred (accidentally) a pair of Kenyi before, and this behavior seems very similar to the female when she was brooding.  Now the questions are, would a female cobalt perform this digging behavior (While brooding?  Wouldn't she spit the eggs out with the gravel?), and become aggressive when defending her nest?  Also, would it be possible for the cobalt to breed with either the Kenyi or the yellow labs or could this be some sort of 'phantom brooding', or possibly even holding an unfertilized clutch?  Thanks for any assistance.

 Jake

Answer
Hi Jake,
 Yes, the cobalt could easily breed with one of the other fish.   It is highly unlikely that a fish that is holding eggs would do any digging.  Female cichlids that are holding tend to be very inconspicuous and often hide a lot of the time, trying not to draw attention to themselves.  Furthermore, if a female that was holding did grab some gravel and get it in her mouth, it would quickly grind up the eggs.  Even a single piece of sand/gravel in her mouth can be the end of the whole clutch.

-- Ron
  rcoleman@cichlidresearch.com
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