The new kitten and Fish seem to have accepted each other. Mild play sessions have even been observed, generally consisting of chasing each other around the sofa but never making physical contact. Agatha, on the other hand, continues to hiss and growl at any siting of the kitten, and won't enter a room if the kitten is there. Agatha does defend the bed as her territory, and the kitten has apparently learned to either not go there or get off quickly if Agatha's around.
The name search might be settling in on Fred, short for Winnifred from Once Upon A Mattress. The song "I've always been shy" particularly resonates, as does lung power reminiscent of the young Carol Burnett in the role. Choruses of "I'm in love with a girl named Fred" are also appropriate.
There were brief mentions of calling her Squirrel for her magnificent tail, but Squirrel is a little difficult to pronounce. I did want to name her Ista, but the pronunciation again stopped me--that first syllable kept coming out like a hiss. Suggestions by the nieces to riff off Fish were also rejected. (No, we're not calling her Chips. Or Shark Bait.) Nephew's suggestion of Suzie after a classmate was also rejected. So we're giving Fred a test run, and unless some other name manifests itself, Fred will probably stick.