Transporting and Shipping Fish

How to move fish safely: fasting beforehand, bagging with oxygen or breather bags, temperature protection, and acclimating them on arrival.

Fast before transport

Do not feed the fish for 1-2 days before shipping or a long move. An empty gut produces less waste in transit, which slows the buildup of ammonia in the enclosed water and keeps conditions safer for the journey.

Bagging and oxygen

Use as much water as practical so parameters stay stable and the fish has room to move. Many shippers use gas-permeable breather bags, which let oxygen enter and carbon dioxide leave; air is squeezed out, the neck twisted, knotted, and secured with a rubber band. For bettas or spined fish, a sealed bag filled two-thirds with water and one-third with air is used, double-bagged for safety. Splitting fish across multiple bags, or one per bag, limits losses if a bag fails.

Temperature protection

Insulate the box with foam board or polystyrene sheet. In cold weather a long-duration heat pack is added; in hot weather a wrapped ice pack is used. Place packing material or cardboard between the bags and the heat or cold pack so the fish are not exposed to a temperature extreme.

Why arrival is risky

During transit, ammonia and carbon dioxide from respiration and waste accumulate in the bag, lowering pH. When the bag is opened, carbon dioxide escapes and pH rises quickly, converting accumulated ammonia into its more toxic form, which can damage gill tissue. This is why opening and acclimation must be done carefully.

Acclimate on arrival

1. Float the sealed bag in the tank for about 10-15 minutes to equalise temperature (breather bags float on the lid for 30-60 minutes).
2. Pour the fish and bag water into a clean container so they are fully covered.
3. Add tank water to double the volume, wait, then double again and once more over the next 20-25 minutes.
4. Net the fish into the aquarium without adding the transport water.

Minimise time

Keep the total time in the bag as short as possible. Take the most direct route home from a store, and schedule shipments to avoid weekend or holiday delays so the fish arrive sooner.