Kribs and Severums

Question
I have a 23 show-front with 3 kribs, four small green severums (temporarily), and a few white clouds acting as dithers. They all seem to get along well, except that two of the kribs are facing off constantly - flared fins, lip-locking, chasing one another, et al. The third krib, of equal size with the fighters, is completely ignored by the combatants.

The two aggressive ones both have a bright red line along the top of the dorsal and the edge of the caudal fins, but neither have the pointed tail of a male. No one has a big red tummy as of yet, so I'm guessing they're males - but the round tails have me stumped! They were bought as P. pulcher, but could they be a different subspecies...?

The tank is neutral, slightly hard well water with plenty of hiding places and territory-breaking screens. They are all greedily accepting frozen brine, but only the white clouds and severums are interested in flake or freeze-dried bloodworms. Should I offer the kribs something like zucchini or spinach?

All of my cichlid experience is with South and Central American species (discus, angels, uarus and the like); this is my first try at Africans of any sort. The severums will be moving to a tank of their own very soon.

Any suggestions on how to sex these two?  

Answer
Hi Amy,
  Look closely at the pelvic fins (the paired fins on the bottom).  How would you describe their shape and are they the same in all three individuals?

-- Ron
  rcoleman@cichlidresearch.com
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