There have been a number of koi related crimes lately with the BBC reporting only the other day that " Thieves take £3000 of koi carp". I doubt the thieves were professionals and knew what they were doing, or know how to look after the six big koi that they took. Hopefully they are well and the police can get them back into safe hands, but somehow I doubt it.
One of the problems with koi thefts is the police don't realize how attached owners can become with their koi as pets as well as them being unique creatures which are not easily replaced. People generally who don't keep koi tend to view them all as costing thousands and an exotic play thing for the very rich & famous like owning a racehorse, but this as we know isn't true. The press reports don't help much either and tend to marginalise the hobby with reports that thieves try to sell the koi on to collectors. By collectors I take it they mean koi keepers but the term kind of suggests someone similar to an art collector. There isn't a big market for second hand koi and serious koi "collectors" wouldn't dream of buying koi from unknown sources. This leaves the thieves to approach koi dealers who would probably twig that they are not genuine or give them a lot less than they were expecting. A likely senario is they will end up in an unsuitable pond with owners unlikely to be able to care for them.
This got me thinking that we should all try to keep our koi secure no matter how expensive they are. Not only the koi themselves but also the many other pond accessories can be attractive to burglars. This shouldn't be something to worry about but there are many things that can be easily done. Security cameras, webcams and intruder activated lights are increasingly becoming more affordable. I have even seen an underwater camera advertised so you can check you koi when on holiday. For large, expensive koi an experienced vet can microchip them if you wish, which involves injecting the tiny chip under the scales, similar to the chip used on cats & dogs. How successful this is I don't know but it makes sense to first try to prevent them from being stolen, before considering it.
There is a website Pond watch UK that reports koi crimes from around the UK , which should be useful to koi dealers and owners. It relies on the crime victims updating the site but should help to deter koi criminals targeting ponds and people buying stolen koi. Like anything common sense is needed and if anyone offers you koi that you are not sure about then walk away.