Question
Hi.I have a 18" long and about 10lbs mirror carp that is now laying on its side at the bottom of my pond.It spends longperiods of time like this and then will swim slowly about for a short time before going back to the afore mentioned position.Any ideas,thank you

Answer
It seems this happens to a lot of koi.  I'm not sure of the cause though.  Most any illness can result in that listlessness, trouble swimming or staying upright, etc. That includes bacteria, parasites, swim bladded disorders, aging, etc. There may be an internal bacterial infection but as for a definitive diagnosis, that would require doing scrapings under a microscope to rule out parasites and sending samples out for bacterial analysis.  There are koi vets who would do tests for you if you can find one.  There is a lab that tests koi tissues and live koi too (they always kill them after though) if you want me to find that information but it's in the US.  Also, check out http://www.koivet.com

Good luck!