How to Care Koi Fish

KOI FISH CARE -- Koi Pond depth also needs to be defined. A pond 2 meters deep is considered deep. A pond 3 meters deep is considered a tourist attraction. A pond 1 meter deep is considered shallow by many enthusiasts. Ponds below 50cm should not have Koi in them. I agree, however, there are many Koi keepers who have ponds and water features that are 50cm deep. They have Koi living quite happily in them.
We can confidently define a deep pond as a pond that is 2 meters or deeper. Shallow ponds are defined as 80cm - 1.2 meters in depth. Anything in between is a medium depth pond.

Argulus Koi Parasite

Argulus (Fish Lice)  parasites for koi fish can be commonly introduced into koi ponds by frogs and toads. Argulus (aka Fish Lice) are more developed than most of the other parasites. You can see them quite well without using a microscope. They move around and itch the fish and cause complications that can kill koi and goldfish.