to Koi pond keepers) to secretly put fish into the pond and surprise the receiver (who is supposed to discover an unexpected fish in his pond in the next day and be happy about it) this way. This has led to complete losses of very valuable (intangible and material) Koi stocks due to disease outbreaks (e.g. by newly added Koi that had the Koi Herpes Virus, KHV, in them) - and that can never be…