Reel McKoi wrote:
"Peter Breed" wrote in message
...

Having watched my fish for the last sixth months I think the fish I
bought with longer fancier tails seem be changing shape, their tails
appear shrinking to match their shorter tailed pond mates. They all
appear healthy and the shorter tail appears to be making them faster and
more maneuverable.
I was just wondering if anybody else had observed anything similar?
Peter

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My long finned koi's fins get longer as they get older. The same thing
happens to the goldfish. I have never seen fins get shorter over time
unless the ends were diseased in some way.

I wondered if they were adapting to pond shape, I can envisage a long
being an advantage in still waters over a long distance, and short tail
being advantage in fast flowing waters. My pond is quite small at about
about 6ft x 3ft (excluding the planting shelves) but 3.5ft deep in the
main area.

As I said the fish appear healthy, and my pond is not heavily stocked (4
Comets and 3 Shubumkins only two are larger than 3-4inches) - I wasn't
particularly worried, just curious. I wondered I was observing a common
phenomenon.