Koi Health - Information on Koi Herpesvirus

Where to draw the blood?

The folowing two images are enlarged to show detail. The tail has been removed from a fish which has been euthanized due to a tumor. The section is just posterior to the anal fin. The koi is held upside down such that the ventral surface is up. You are looking from the tail towards the head. The anal fin is visable at the top of the photo. The needle is a 11/2 inch 22 gauge with the tip in the area of the caudal vein.

Ventral approach to drawing blood from the caudal vein...

Drawing blood from koi overview

Anatomy enlarged for venipuncture reference..

Enlarged and labeled illustraton of caudal vein for venipuncture

By drawing blood from this area by the ventral approach, there are no critical organs for the needle to penetrate between the surface and the vein. If a scale is damaged, it is not visable from above while healing.

Blood drawing in practice...

One essentially inserts the needle in the midline, aiming for the center of the vertebral body. In smaller and medium size koi, one feels resistance at the vertebral body and then gently withdraws the syringe plunger. If blood does not immediately flow, the plunger is released and the needle repositioned. If suction is maintained on th plunger while repositioning the needle, the usual result is a cloged needle. In very large koi, It is a matter of positioning as the scales and tissues are very thick and tactile sensation is markedly reduced. Different techniques for supporting the koi are utilized depending on size of koi and personal preference. Examples follow here and on other pages. The site of venipuncture is swabbed with betadine before the fish is measured, photographed, and returned to the pond.


In this case, the koi is immersed in aerated water and the tail is held with a wet towel. The watch should have been removed before handling koi.

Venipuncture, drawing blood for serological testing

Blood is withdrawn form the caudal vein.

Drawing blood from caudal vein of koi for KHV serology

One ml of blood is more than enough.

disinfecting venipuncture site with iodine solution

DIsinfecting the venipuncture site with iodine solution.

Transferring blood to serum tube for KHV serology

The blood is transferred from the syringe to the sterile sample tube. As the tube is under a vacumn, the syringe plunge is initially held to prevent the rapid flow of blood from the syringe. The needle is usually held against the side of the tube as well. These measures are important in reducing red cell hemolysis.

Drawing blood for KHV serology, alternative technique

For some reason, it helps to hold the needle cap in one's mouth.

WIthdrawing blood for KHV serology

Gently withdrawing blood.

Drawing bloood for KHV serology

Recovery in measuring and photo tub

Recovery in measuring and photo tub.

After blood is obtained in the syringe, it must be prepared for sending to the laboratory for serological testing.

More photos of drawing blood.