"gng" wrote in message
...
Should I be concerned? I have a 2500 gallon pond with water lillies and
about a dozen koi (18") and a dozen goldfish. Lately I've noticed the koi
are all hanging out under the waterfall. Nothing has changed - they never
used to do this. They eat fine, and otherwise no issues. Is it posible
they need more oxygen, or do they just like hanging out there?



You hit the nail on the head. They need more oxygen. The first to suffer are
the big fish as these need more air. You may need to react straight away or
you could loose them. Sorry, but that`s it. Keep the waterfall going in hot
and/or thunderey weather. This takes the O2 out of the water.

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IAN. P. GARDNER
ISLE OF WIGHT
www.gardner44.freeserve.co.uk