What to look for when you want to buy Koi fish

Koi Dealers

The dealer you are buying your Koi from should have a clean facility. A dealer can have a much higher stocking density than a hobbyist since the he holds Koi won't be there for an extended period of time. The tanks that house the Koi should not be over stocked and the should either be placed a few feet apart or they should have a barrier in between. If your dealer has a shipment that is under quarantine, you don't want to purchase a Koi from a tank that is potentially compromised.  The water the fish are in should be clean with adequate filtration to support a heavy fish load.
 
You dealer should quarantine and perform virus tests on each of his shipments.  Avoid any dealers that fly a shipment of Koi in and then immediately offer them for sale.
 

Health

The Koi you are looking at should be healthy.  It should exhibit normal behaviour.  If you notice the Koi flashing (scratching itself on the side of the tank) avoid it, it could have a parasite problem. Look the Koi over for any visible parasites and ulcers.  Inspect other Koi at the dealer, if you notice a lot of health problems with their fish, you may want to go somewhere else.
 

Appearance

The following criteria are used to select a beautiful Koi fish:
 
Body Conformation
 
The body of a Koi fish should be symmetrical, with no physical deformities.  Female Koi are preferred over males, due to their body shape when they mature.  A mature female with have a large body that has a blimp-like shape.  A mature male will have a cigar-like body shape.
 
Skin Luster
 
The condition of the skin greatly affects the appearance of the colour.  If a Koi is sick, is malnourished, or if it is in a bad
environment, the skin quality suffers along with the colour.
 
Quality of Colour
 
The colour should be even throughout the fish.  If you were
looking at a Kohaku, you would not want spots of red that were darker than others.  Keep in mind that the colour on the head will look different on the body since it won't be diffused by the scales. Inspect a Koi for any colour loss.  It will be a patch or part that will look faded.  Colours should be strong, for instance, the white should be bright with no yellowing.
 
Pattern Edge
 
The edge of the colour pattern should be defined.  Blurry edges will look worse as the Koi grows.
 
Pattern of Colours
 
The colour should be evenly distributed across the top of the body of the fish.   A Kohaku with red patterns towards the back of the fish will look less impressive than one with a stepping stone pattern down its back.