Question
Hi

I've recently moved house and to my surprise inherited a pond with 9 fish in it from the previous owner.  The pond is about 2m x 2m, maybe a little more.  Some of the fish look to be koi and some may be large goldfish.  Recently, one of the fish has been found lying on its side at the bottom of the pond.  I went to scoop it out but it is still alive.  Any ideas?  There is a pump system running in the pond and two waterfall things to aerate.

Answer
Dear Rob,

Thank you for your question.
It seems the fish is not healthy (however is can also be due to the cold if there is ice on the pond and when it is cold A log time).
From A distance it is hard to tell.
However we first look for some visual signs on the fish:
Red areas, wounds, fungus, parasites.
Then we also check the water with tests
Next step is to look with microscope (only possible if you are experienced :-( )
Then we decide what to do.
So best way is to start with taking A close look at the fish.

Good luck!
Kind regards,
Raf