Complete guide to pure oxygen packing, water ratios, bag sizing, Styrofoam insulation, and heat packs. The exact protocols Bluefields Aquatics uses to achieve sub-2% DOA on every international shipment.
This guide is brought to you by Bluefields Aquatics, a licensed marine ornamental fish exporter based in Mtwapa, Mombasa, Kenya. We export to 67+ countries with full documentation.
Packing is the difference between a good fish and a dead one
You can collect the healthiest marine ornamental fish in the Indian Ocean, hold them in perfect water, and still lose the shipment if the packing is wrong. Packing for live export is a discipline in its own right — part biology, part chemistry, part physical engineering — and it is the stage where a professional exporter earns the trust of an importer. This guide explains the standards Bluefields Aquatics packs to, the reasoning behind each step, and what you should expect to see when you open a properly packed box.
Conditioning before the bag
Good packing begins before any water touches a bag. Fish are fasted for 24 to 48 hours so that their guts are empty and they produce minimal ammonia in transit. They are handled calmly and as little as possible, because every chase and every transfer adds stress that translates directly into oxygen demand later. A fish that goes into the bag relaxed and purged will consume oxygen slowly and foul its water slowly — the two things that decide whether it survives a long flight.
Water volume and the water-to-air ratio
The single most important packing variable is the ratio of water to oxygen in the bag. Too much water and there is not enough oxygen headroom for a long flight; too little and the fish has no thermal buffer and fouls its environment quickly. As a general principle we use roughly one part water to two or three parts oxygen by volume, but the exact ratio is adjusted for species, fish size and transit time. A small damselfish on a short route is packed very differently from a large angelfish on a 30-hour journey.
The water itself is clean, mature, temperature-matched saltwater drawn from the holding system the fish has acclimated to. We do not pack into freshly mixed water, which can shift pH in transit. For most marine species we also avoid freshwater dips before packing, as these are harmful to stenohaline marine fish; where a prophylactic treatment is warranted we use a controlled saltwater-based protocol instead.
Oxygen, not air
Every bag is charged with pure oxygen from a cylinder, never with room air, which is only about 21% oxygen. This is so important that we devote a separate oxygen bagging guide to it. Pure oxygen extends the safe transit window by hours and is the main reason a fish can survive a multi-leg international journey in a sealed bag.
Bagging technique and spiny species
Bags are rounded at the corners or doubled so that a fish cannot wedge itself into a corner and suffocate. The neck is sealed with strong bands in a way that traps the oxygen charge without crushing it. Species with spines or sharp gill plates — lionfish, surgeonfish and tangs, triggerfish, certain catfish and eels — are double or triple bagged, and sometimes the spines are managed with a breathable inner sleeve, so that a single puncture cannot deflate the package and drown the fish.
- Tangs and surgeonfish carry a scalpel at the base of the tail; they are bagged so the blade cannot slice the bag. See our tang buyer guide.
- Lionfish and scorpionfish are venomous-spined and always multi-bagged.
- Moray eels are strong and abrasive and are packed individually in heavy bags.
- Large or aggressive fish are packed one to a bag to prevent injury.
Insulation and the box
Bagged fish are packed into lined polystyrene boxes inside an outer carton. The polystyrene holds temperature stable against the cold of an aircraft hold and the heat of a tropical tarmac, both of which are lethal in excess. Where a route runs through cold transit points, heat packs are added; where it runs through hot ones, the insulation and water volume are tuned to resist warming. Boxes are filled so that bags cannot shift in flight, because a sliding bag is a leaking bag.
Every box is labelled as live tropical fish, marked for upright handling, and accompanied by the correct paperwork — CITES permits where required, KEPHIS health certification, and the commercial documents your customs clearance depends on. We cover the documentation side in our CITES guide.
Matching the pack to the route
There is no single correct way to pack a box; there is only the correct way to pack this box, for this species, on this route. The transit time from Mombasa or Nairobi to your airport drives every decision — water volume, oxygen charge, insulation and whether heat packs are needed. This is why we plan packing alongside airline routing rather than treating them separately, and it is a large part of how we hold our DOA under 2%.
What a good box looks like on arrival
When you open a Bluefields box, the bags should be cold-stable but not chilled, the water should be clear rather than cloudy, and the fish should be upright and responsive. A faint amount of waste is normal after a long flight; heavy fouling or strong ammonia smell is not, and indicates a packing or conditioning failure somewhere upstream. Learning to read these signs, and then following a careful acclimation, gives your fish the best possible start.
If you would like to receive a sample of our packing standard, request the current stocklist or get in touch to plan a first shipment.
Frequently Asked Questions
How are marine fish packed for international shipping?
Each fish is bagged in clean, temperature-matched saltwater with a water-to-oxygen ratio tuned to the species and journey length, then the bag is charged with pure oxygen and sealed. Spiny species are double or triple bagged. Bags go into lined polystyrene boxes that hold temperature stable, with heat packs added on cold routes. Every box carries the correct CITES, health and commercial paperwork. The whole pack is matched to the actual transit time of your route.
Why is the water-to-air ratio so important?
The ratio of water to oxygen determines whether a fish has enough breathable gas for the journey and enough thermal buffer to survive temperature swings. Too much water leaves insufficient oxygen headroom for a long flight; too little leaves the fish without a buffer and fouls its environment fast. A typical ratio is around one part water to two or three parts oxygen, adjusted for species, size and transit time.
How are spiny fish like tangs and lionfish packed?
Species with scalpels, spines or sharp gill plates — tangs, surgeonfish, lionfish, triggers, eels — are double or triple bagged, and larger specimens are usually bagged individually. This prevents a single spine from puncturing the bag, which would deflate the package and drown the fish and its bagmates. An exporter’s handling of tangs and lionfish is a good test of overall packing competence.
What should a properly packed box look like on arrival?
The bags should be cool but not chilled, the water clear rather than cloudy, and the fish upright and responsive. A small amount of waste after a long flight is normal; heavy fouling or a strong ammonia smell indicates a packing or conditioning failure upstream. Bags should be snug in the box so they did not shift in flight, since a sliding bag is a leaking bag.
Do you use freshwater dips before packing?
No. Freshwater dips are harmful to stenohaline marine fish and can cause more damage than they prevent. Where a prophylactic treatment is genuinely warranted, a controlled saltwater-based protocol is used instead. Fish are packed into mature, temperature-matched saltwater drawn from the system they acclimated to, not freshly mixed water that could shift pH in transit.