Koi fish's treatment is best not to have an injection unless it is absolutely necessary. Drugs can be added to the feed and stirred evenly before feeding. If fish can't feed themselves, they can be forced into their mouths. If you have to use an injection, please go to the flower, bird, fish and insect market for consultation. (Note: If you want to operate by yourself, don't puncture the muscles of the fish, pay attention to disinfection, and strengthen the observation of fish for abnormalities. For reference only)