It is really essential that you do have a selection of good bowls from the small 22 inch diameter ones up to perhaps, depending on the size of your largest Koi 100 cm.
Handy bowls in various sizes for temporarily holding, showing, treating, or transporting of your fish. The fish can be kept in the bowl for several hours without any problems if you place an air pump in the bowl and cover the bowl with a lid. Refresh the water regularly.
Bowls should always be cleaned out thoroughly after use and remember to do this every time, it is no use grabbing a dirty and possibly contaminated bowls when you urgently need one to treat one of your koi.