Comet tails

Moments before spontaneously combusting humBill at
was heard opining:

Hi all
Here in Austin we have had a particularly mild winter. Nonetheless
the fish have not be active and I have not been feeding them for
about three months. They have pretty much been out of sight hunkering
down under a bunch of anacharis I have been letting grow, as possible
protecting from an occasional Heron visit. Now that I have begun
feeding again and they are out and active I am noticing a problem.
Some tails on the comets who have the longest tails seems to be
splitting somewhat.

It may be time for a partial water change. Is there a lot of decaying
debris on the bottom along with the anacharis? Start by checking the PH to
see if it dropped over the winter.

My first thought is fin rot, but I don't see any
loss yet and the water parameters are perfect. It is only the ones
with very long, flowing finnage.

What were the parameters? How high were the nitrate readings?

While not as extreme it is vaguely
reminiscent of how a flag sometimes shreds on the back end from
whipping in the wind, except the splits are not as numerous and are
longer (1"-1 1/2").
Any thoughts on what may be causing this? Is it a concern? What
remedies might I try. I thought about adding some Mela Fix but I
don't want to waste money needlessly.

Before adding anything - what were the parameters and when was the last
partial water change?
--
Koi-Lo.... frugal ponding since 1995...
Aquariums since 1952
My Pond & Aquarium Pages:
http://tinyurl.com/9do58
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