How to Safely Transport and Ship Koi Fish: Bagging, Oxygen, and Acclimation
To transport koi safely, fast the fish for 48 to 72 hours beforehand to clear the digestive tract, place each fish into heavy-duty 3-mil rounded-corner polyethylene bags containing one-third water and two-thirds pure pressurized oxygen, double-bag with seams reversed, and pack inside an insulated polystyrene box. Acclimate upon arrival by floating the bag for 20 minutes to equalize temperature before releasing the fish without bag water.
Key Takeaways
- Fast koi for 3 full days prior to transport to prevent ammonia fouling inside the bag.
- The bag ratio must always be 1/3 water to 2/3 pure compressed oxygen—never room air.
- Use rounded-corner bags and double-bag with reversed rubber bands to prevent leaks and corner trapping.
- Never dump transport bag water into your pond or quarantine tank; net the fish out cleanly.
Pre-Shipment Fasting: The Critical Ammonia Rule
The primary cause of mortality during fish transport is not lack of oxygen, but autointoxication from excreted metabolic waste. When fish digest food, their gills excrete large amounts of unionized ammonia, and their feces pollute the confined water.
All koi must be strictly fasted for 48 to 72 hours before being packed into transport bags. Fasting empties the digestive tract, dramatically lowering ammonia production and biological oxygen demand during shipping.
Professional Bagging: The 1/3 Water to 2/3 Oxygen Ratio
Standard polyethylene bags with sharp square corners can pinch and suffocate koi that wedge their heads into the corners. Use professional rounded-corner gusseted shipping bags (at least 3 to 4 mils thick).
Fill the bag with only enough pond water to comfortably submerge the fish (approximately one-third volume). Compress the remaining headspace to expel ambient room air, insert an oxygen wand, and inflate the remaining two-thirds of the bag with pure medical or welding-grade compressed oxygen gas. Pure oxygen dissolves under slight pressure, sustaining the fish for 24 to 36 hours.
Double Bagging, Insulated Shipping, and Acclimation
Always slip a second bag over the first in the opposite direction and secure each separately with heavy rubber bands; this ensures that even if the inner bag suffers a fin puncture, the outer bag retains water and pressure. Place bags inside thick-walled styrofoam shipping boxes lined with newsprint.
During transit in hot weather, tape a wrapped ice pack to the inner lid (never directly against the fish bag) to maintain water temperatures below 68°F (20°C). Upon arrival, float the sealed bag in the quarantine tank for 20 minutes to equalize temperatures within 2°F before netting the fish into the tank.
Step-by-Step Packing and Acclimation Checklist
- Withhold all food from the fish for 3 full days prior to travel.
- Add a mild water conditioner and 0.2% salt to the packing water to ease stress.
- Fill a heavy 3-mil bag with 1/3 clean pond water and introduce the fish head-first.
- Evacuate atmospheric air and charge the remaining 2/3 of the bag with pure pressurized oxygen.
- Twist the neck firmly, fold over, and bind with multiple heavy-duty shipping rubber bands.
- Invert and slide into a second bag; seal the opposite end with rubber bands.
- Pack inside an insulated cooler box with thermal gel packs as required by weather.
- Float the sealed bag in quarantine water for 20 minutes; net fish out and discard all bag water.
Recommended Reading & Resources
Explore our comprehensive guide on How Do You Prepare Water For Koi? to learn more about preparing pristine dechlorinated quarantine water for newly arrived koi.
Explore our comprehensive guide on How Do You Identify Koi Disease? to learn more about inspecting freshly transported fish for transport abrasions and fin tears.
Common Questions
How long can koi survive inside a shipping bag?
When properly packed with pure compressed oxygen and fasted water, koi can survive comfortably for 24 to 36 hours in transit.
Why should you never pour transport bag water into your pond?
During transit, carbon dioxide accumulates in the bag, depressing pH and converting toxic ammonia into non-toxic ammonium. Opening the bag releases CO2, rapidly raising pH and turning ammonium back into lethal free ammonia, while releasing concentrated bacteria into your pond.
Can I use an air compressor or bicycle pump instead of pure oxygen?
No. Atmospheric air contains only 21% oxygen and 78% nitrogen. In a sealed bag, ambient air will deplete within 2 to 3 hours, causing fatal asphyxiation. Pure compressed oxygen is required.