Fact: Amikacin is an ‘aminoglycoside’ antibiotic which is taxing to the kidneys / nephron and can cause kidney damage AND death in fish treated with it. THE MOST PREVALENT reason for this is overdosage and the most FREQUENT form of overdosage it the INTERVAL it’s used in.
FACT: Studies show that Amikacin stays in the Koi / Carp body for up to ten days.
FACT: Amikacin still being in the tissues does NOT mean there’s enough to kill target germs.
FACT: Amikacin has been used successfully and safely in Koi by several routes including in the belly, in the muscle.
PREVAILING THOUGHT ON AMIKACIN DOSING In KOI CARP GOLDFISH and Ornamental fish:
There are multiple published amikacin regimens in fish, and some internet sources still repeat older koi hobbyist protocols.
For ornamental koi/common carp (Cyprinus carpio), the most commonly cited veterinary references from Lewbart and other fish medicine formularies use:
- Amikacin: 5 mg/kg
- Route: Intramuscular (IM) or Intracoelomic (ICe)
- Interval: Every 72 hours (q72h)
The more recent trend among aquatic veterinarians is generally to favor intramuscular injection in sufficiently large koi because dosing is more reproducible and tissue distribution is predictable. Intracoelomic administration is still described and used, particularly in some species and circumstances, but IM is commonly preferred when practical.
Commonly Referenced Koi/Carp Protocol
| Drug | Dose | Route | Interval |
|---|---|---|---|
| Amikacin | 5 mg/kg | IM | Every 72 hours |
| Duration | Typically 3 treatments, sometimes longer if culture/sensitivity supports continued therapy |
Why the Dose Is So Low
Amikacin is an aminoglycoside. In fish, especially koi, it is valued because it can be effective against many gram-negative pathogens, but it carries a well-recognized risk of nephrotoxicity. That concern is one reason many aquatic medicine references use relatively conservative dosing intervals (every three days rather than daily).
A Note About the Conflicting 20 mg/kg Recommendations
You may encounter koi websites and hobbyist references recommending 20 mg/kg IM every 48 hours. Those protocols do exist in the hobby literature.
However, when I compare those recommendations with the veterinary fish medicine sources associated with aquatic animal specialists and formularies, the 5 mg/kg q72h regimen is the one most consistently cited for koi/carp.
I’d be reluctant to call any single regimen “the” correct answer without knowing:
- Water temperature
- Target pathogen
- Renal status of the fish
- Whether culture and sensitivity results are available
- Which reference text you’re trying to follow (Lewbart, Divers, Stoskopf, Noga, etc.)
Download Dosing Chart of Amikacin Dosing Per Unit Length of Koi or Common Carp
