"Displaying"?

What do White Cloud Mountain minnow displays mean? Son has a small
(5gal) tank in which he had one survivor from six fish. Wife got four
other fish and we put them in the tank (doing all the leveling of
temperatures etc). The original fish seems to be about one and a half
times the size of the "incomers". Had seen he had white(?) tips to his
fins but today these are almost luminous and he seems to swim along side
one of the incomers and "spreads" his fins (dorsal, anal )showing of
these "luminous" tips is this some sort of sexual display or is it some
sort of "I am head honcho of this shoal" display?

This display was within the first hour or so. Just establishing the
"pecking order"?

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'S rioghal mo dhream
www.cheesesoup.myby.co.uk