Koi College - Koi Health

Injecting Koi A to Z

Injecting Your Koi

The truth is that every Koi Hobbyist will one day need to inject their Koi either with Antibiotics or with a Vaccine. Now, you could pay a vet to come to your house and inject your Koi for you, but the procedure is actually quite simple.


Everyone is afraid to put their Koi to sleep. Using anesthesia on Koi is not that hard. Actually the procedure is quite simple and much less stressful on the Koi and us when we need to treat a sick Koi. We have all read articles and medical studies on Koi that show stress as a major contributor to diseases and even death. Once we have learned how to properly and safely sedate our Koi, we will be able to administer first aid a lot easier. Even though it is not difficult to perform, anesthesia is not without some risk. However, adequately and humanly treating your injured or sick Koi should be our most concern. Two types of recognized anesthesia. One is fairly cheap Clove oil or “Oil of Cloves” sometimes labeled “Eugenol.” It can usually be found in most large pharmacies and health food stores in liquid form in small bottles. The proper dose is 5-10 drops per gallon of water. Begin with 5 drops per gallon and wait about 10 minutes. If you’re Koi hasn’t rolled over on its side or is sedate enough to be worked on with little movement, add 2-3 more drops per gallon and wait ten more minutes.Another great option but a little more expensive is a product called MS-222 or Tricaine Methanesulfonate. Common brand name is Tricane-S. This is a commercial fish tranquilizer in a powder form and will have to be bought from a large pond or Koi supplier. Dose exact according to product label directions. This is a very good and safe product.

How to use Anesthesia:

1. First have everything you are going to need to treat you sick Koi set up and handy to begin with. You will need two containers large enough to hold your Koi and some pond water. The first container is where you will use the anesthesia and the second is to revive your Koi after treatment.

2. Place enough pond water in both containers to allow the Koi to float comfortably. Do not use containers too large or you will need to use greater amounts of anesthesia. You only need enough water to barely cover the Koi. Have a cover for the container to prevent your Koi from jumping out and possibly getting injured. The net you use to catch your Koi will work fine.

3. Use surgical gloves to handle your sick Koi.

4. Measure the anesthesia into a small glass jar with a small amount of pond water. Shake the mixture until it is completely dissolved. Using warm water with clove oil will help emulsify the oil based product. Pour into the first container.

5. Use an air stone to aerate the water in both containers.

6. Carefully catch and place the Koi into the first container with the anesthesia. Cover the container. Check the time. Observe the Koi carefully through this entire process. The breathing will slow and the gill plates will slow down. It may want to struggle at first so cover the container. It usually takes about 5-10 minutes for the Koi to go under. If it seems unaffected by the anesthesia after ten minutes place additional water from the tub back into the glass jar, add some additional anesthesia (perhaps 50% of original dose) mix well and pour into the container with the Koi. You might have to do this a few times until your Koi starts to sit on the bottom and eventually it will lie over on its side breathing slowly. Larger Koi will take a little more anesthesia.

7. When you can pick it up and it doesn’t want to struggle or flop around it is ready to be treated. Its gills covers will still be moving slowly.

8. Keeping the sedated Koi in the water, take the time to exam its body fully. The underside can hide ulcers or other problems that are not detectable while it is swimming free in the pond.

9. Any ulcers, anchor worms, etc. should be treated at that time.” I put Ulcer Aid Rx Powder directly on any wound at this time and let it soak in as I perform any other operation.”

10. Ready to inject you’re Koi: Have all injections and materials prepared before sedating the Koi. Place Koi belly up, cradled on a plastic bag or wet towel. Hold the fish with one hand gently and quickly make the injection.

11. With your treatment complete, now place Koi gently into the clean water container until it revives. Make sure the fresh water container has lots of aeration. Once the Koi uprights itself and starts swimming it can be placed back into your pond or tank. This normally happens very quickly when the sick Koi is placed into the clean aerated water container. Moving the Koi back and forth, to add water flow over the gills has proven helpful in reviving the Koi. Do not release the Koi until it is upright and swimming freely.

12. You’re done

Injection Descriptions:

There are three injection sites on a Koi; Intramuscular (IM), Intraperitoneal (IP), and Intravenous (IV).

1. Intramuscular (IM) is my first choice for injection and is used if the Koi has ulcers that have broken through to the body cavity. Any medication injected into the peritoneal cavity in a fish of this condition could drain out through the ulcer. The ball muscle at the base of the pectoral fin, this is a very popular site as it does not have any scales and has a very high distribution capability, via the pectoral girdle, as the description suggests you insert the needle at the back of the pectoral fin in the ball muscle. Another popular site is under the base of the caudal peduncle, again in the tail muscle, this has the distinct advantage of, if an injection related infection sets in as a result of the injection itself, it will not show a scar, and much the same can be said of the pectoral ball muscle. Injections given into the muscle, diffuses into the tissue and then into the blood stream, then the circulation of the substance begins. The draw back to IM is that the muscle tissue of the Koi will contract and force some of the injected material to be squeezed back out the injection site.

Intramuscular (IM) is my first choice for injection

2. Intraperitoneal (IP) is the second most common & effective method. Antibiotics or vaccines injected into the peritoneal cavity are absorbed into the Koi’s system slowly as opposed to oral medication which will mostly pass straight through. IP injection is performed under sedation so the Koi does not thrash about. Without the thrashing, you will not lacerate an organ. In addition, with the fish relaxed & upside down, the organs tend to settle out of the way a little. You might still puncture an organ, but with the fine needle pushed in and pulled out cleanly, there will be little danger of injury.

3. Intravenous (IV) as the name implies involves delivering the medication into a vein of the Koi; this involves an injection site under the caudal peduncle just ahead of the caudal fin. The main vein run directly under the spinal column, so the needle is inserted vertically at this point until it comes up under the spine and actually very lightly hits the spine, at this point the syringe is withdrawn away from the spine a very minute distance about 1ml the actual point of the syringe should now be in the vein. A slight pull back on the syringe plunger should draw blood into the main body of the syringe, this is an indicator that you are in the exact spot needed and at this point you should depress the plunger and deliver the medication. Although I have seen IV injection in school and have drawn blood for test, I have never injected Intravenous Antibiotics or vaccines myself. Schools warn against this type of injection and reserve it for experts and then only on really large fish. The problem is the ability to actually hit the vein which runs through the center of the fish. It is performed on the under side of the fish near the tale.

I have drawn blood for test in school, but I have never injected Intravenous Antibiotics

Eliminating air from the syringe

This is a very easy technique and essential, if air finds its way into the blood stream an embolism takes place end result dead Koi. After filling the syringe hold up the syringe vertical with the needle pointing upwards pull back on the plunger to create space about 2/3 ml from the top of the syringe this in effect has created an air gap at the top of the syringe, now repeatedly flick the plastic side of the syringe with your finger nail until the air bubbles in suspension in the antibiotic rise and burst on the surface of the fluid. After all evidence of air in suspension has gone, while still holding the needle vertical push the plunger up till the fluid rises out of the top of the needle and no more air can be seen, ready for injection.

The following are injectable tables.

These are set forth to help Koi keepers help themselves, and to get help from their family veterinarian. Injections should never be given unless a veterinarian has approved the use, or knows the Koi keeper well.

Baytril - Enroflaxacin. A fluoroqiunolone antibiotic sold by Bayer Corporation. It is a bacterial agent. The activity of enroflaxacin is concentration dependent-which means dosage has to be precise-a major reason why some will complain that Baytril doesn't work. Susceptible bacteria cell death (gram-negative and gram-positive) occurs within 30 minutes of exposure.

Baytril injectable antibiotic is available in three strengths: 2.27%. 5% and 10%. The table below is calculated for 2.27% Baytril. Baytril in most cases should be the first injectable to use. It is powerful, forgiving, and in almost every instance healing is visible after three injections. The protocol for Baytril is three injections on consecutive days, then two more every other day (EOD) for a total of five injections. Like antibiotics for pets or yourself, it is best to follow through completely. Short-circuiting the injections will lead to Baytril resistant strains. Intraperitoneal injections are usually suggested and are the easiest and safest. Keep this product cool or refrigerate. Baytril is dated and has a fairly long shelf life.

One more thing about Baytril. There have been some cases of new imports being resistant to Baytril. While I know this may be true, it can also look like Baytril resistance when it is actually under dosing of the antibiotic. Measure carefully and refer to the charts for accuracy.

A broad spectrum cephalosporin antibiotic which is active against gram-negative and gram-positive bacteria. Naxcel is a powder and can be stored cold for a year or more. Once reconstituted with sterile water it can be refrigerated for about seven days, or, drawn into syringes and kept frozen for up to eight weeks. Generally available in one gram bottles. Use 20CC sterile water to reconstitute this antibiotic.

Nuflor - Florfenicol.
A synthetic antibiotic which is active against gram-negative and gram-positive bacteria. It is believed to work by inhibiting bacterial protein synthesis.

Cefotan - Cefotetan disodium. Available in one gram vial for reconstitution. Rarely used in Koi. Active against gram-negative and gram-positive aerobic bacteria as well as many anaerobes, both negative and positive. This is primarily a human drug.

Azactam: Aztreonam, Systemic. Aztreonam is only effective against aerobic gram negative bacteria. It is reconstituted with sterile water (for our purposes), normally using 3CC sterile water per gram of the antibiotic. Once reconstituted it is good for about three days at room temperature or seven days if refrigerated. If drawn up in syringes and frozen the shelf life is about 30 days at which point it begins to slowly lose potency. Once thawed, it should not be refrozen.

Naxcel, Nuflor and Azactam antibiotics may be used in place of Baytril, if Baytril does not promote healing after the third injection, or if it is not available. The injection routine is the same, but some will need to be reconstituted with a saline solution or injectable water. The table reflects the different dosage amounts for each antibiotic.

1ml = 1cc

Koi length(inches)----5% Baytril-----Naxcel----Nuflor-----Cefotan-----Azactam


The most commonly used syringes are 3CC 25 gauge 5/8". Smaller ones are used on fish which are 2" to 8".

Please note:

There are other charts in published books that use weight over length for dosage rates. I do not have the chart for weight here; but I know it’s more accurate.

I suggest that the first time you try any of these injections, you ask someone with experience to help you. It is always possible to hurt or kill the Koi if the injection is not done properly.

William W. Risher MICHIGAN KOI Office: 586-790-8013 Cell: 586-489-0783

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