4 min read

Helpful Hints: Packing Fish

Written by Russell McAndrews

In the following paragraphs I shall attempt to describe some helpful tips for packing your fish.  Fish can be kept alive for an amazing length of time if packed properly.  The tricky part is the correct correlation of fish, containter, water, air (oxygen), and insulation.  To start with, match the container size to the fish or number of fish being transported.  They should be able to move about freely but a pail should not be so large that a fish could race into the walls when spooked.  Just about any sealable container can be made to work, but the basic advantages of the bag and pail are all that will be covered here.


Over medium or long trips, be extremely careful about who rides with whom.  Murder in this instance would not be hard to solve but it is no less distressing.  In addition, quite frequently, the murdered fish fouls the water killing the murderer, (intact corpse).  Changing the water in the bag or pail mid-trip is not necessary unless the water has become fouled.  Regurgitation, excess defecation, or a casualty in the container are the only conditions warranting a change of water.  If at all possible, you should check on your fish once or twice during their journey.  Quick action is required when you find one or more of your travelers in distress.  Pails or bags which have been sealed with rubber bands can be reopened if necessary to re-oxygenate the water.  If you don’t have the capacity to drop an air diffuser into the container, repeatedly scoop transport water and slowly pour it back in to the container from a foot above the surface.  The water falling through the air picks up oxygen and transfers it to the container as is mixes the shipping water.  Since I prefer to tie bags, with no means of getting into them mid-trip, I’ve used some different methods of emergency oxygenation.  Agitating the bag vigorously, while holding it more or less in one place, mixes the air and water and increases the surface area many fold allowing for an increased rate of gas exchange.  It is always best to position the bag on it’s side, for this as well as shipping, to maximize the surface area.


The most popular means of transport for fish is, by far, the plastic bag.  They come in almost every size feasible from the “box bag” to the 2” x 3” used commercially for Betta splendens, (Siamese fighting fish).  From a bag’s point of view, the problem with cichlids are their spines.  Not very comforting knowledge, but essential to understanding what you’re doing.  It must come as a surprise to no one that spiny fish cause leaks.  A little care when placing catfish and cichlids into a bag can save that bag and many more.  Collapse is a major concern usually, but not always, associated with a “leaker”.  Extreme drops in altitude or excess oxygen diffusion will exhibit the same symptoms.  Collapsed or loosely sealed bags create dangerous corners and folds.  These can trap and suffocate medium or small fish and serve as convenient leverage points for spines to puncture.  In order to circumvent these hazards, secure the bag TIGHTLY, and flip it upside down.  Double bag by placing the inverted bag into another of the same size and secure the second bag.  With some styles of bag, simply spinning the relative alignment of the inner bag will eliminate corners.  Caution is advisable when purchasing plastic bags.  Some are too thin; some the seams let go under pressure.  Personally, I prefer a general purpose 9” x 18”, 3 mils thick.  Thicker bags are more puncture resistant but are not so easily knotted.


When it becomes necessary to transport large amounts of water, the pail is definitely the way to go.  This comes in handy when taking a contestant to show so as not to shock the fish with potentially different water.  Extremely large fish would require a pail.  An inherent benefit with a large mass of water is thermal stability.  If the pail is uncoverred, remember to reduce the water level to prevent leapers from getting out.  A lid, aside from keeping the occupants in, helps to calm the fish by darkening the interior.  Consider that fish need oxygen, oxygen exists at a much higher concentration in air than in water, if the pail  is too full (i.e., little air) open it often scooping and slowly pouring it back.   Bear in mind the walls of a pail are rigid and may be rough.  Excitable fish tend to dart about and hurt themselves.  Another danger along the same lines is scarring, by continuously bumping and circling the perimeter of the pail the mouth and eyes may become permanently damaged as they scrape the walls.  A plastic bag liner would alleviate this problem.  Finally, brace the pail upright.  When subjected to external stresses, (tipping, sliding, rolling), even tightly covered ones can pop open.


Over a short time span, the use of oxygen is seldom necessary.  Nonetheless, I would still recommend using it when dealing with high temperatures or delicate passengers.  (NOTE: the use of oxygen when shipping Corydoras can be fatal to these animals).  The higher the temperature of the water, the less oxygen will dissolve in it.  Obviously, with higher ambient temperatures, the shipping water will become warmer.  Remember to use a high ratio of air to water.  Water enough to cover the fish in an upright position is all that is necessary.  The fishes oxygen supply is primarily the air in the container.


Temperature must be held constant.  Insulation is required for shipping tropical fish whenever the outside temperature is below 65F or above 85F.  If the temperature drops too low the fish will go into shock, usually turning pale and motionless.  Gradually bring this victim back to normal temperature as soon as possible, a lap or tucked inside a jacket will do.  This fish has a higher chance of survival than the victim of overheating.  Gasping at the surface because of oxygen starvation will probably be the first indication that the temperature is too high.  Mad dashes or abandon about the confines of the container are sometimes evident.  This condition requires no only that the temperature be corrected, but also oxygen must be introduced at once.  Styrofoam boxes, coolers, and additional bags are all good insulators.  A bulk of water at the proper temperature is excellent for maintaining thermal stability but heavy for shipping.  Commercially available heater packs are now on the market.  Although these are a proven product, take care to read the instructions.  They will not work if they become wet, but must remain open to circulating air space in order to perform.  They must be used beside or on top of a bag, never underneath.