How to Properly Transport Fish.
Continued…
Travel time from 2 to 24 hours.
For longer-term transportation or during summer heat, it is highly advisable to charge the bag with fish with oxygen. In this case, the container is filled with water only to 20-30% of its total volume, and then the “settlers” themselves are placed inside. Next, the air is let out of the bag by hand, a rubber hose is inserted (immersing it in water), the deflated bag is grasped near the top, and oxygen is pumped in from an oxygen cushion or cylinder. The inner bag is placed inside the outer one. The neck of the bag (5-7 cm) is twisted into a spiral and secured with one or more rubber rings. This amount of respiratory preservative, provided the stocking density is correct, will last until the end of the journey. Please note that this method of transportation is completely unacceptable for labyrinth fishes and catfishes; they need atmospheric air and cannot tolerate pure oxygen.
As you know, a thermos preserves temperature best. Therefore, it will be the most ideal solution for us. However, sometimes a thermal box is not at hand, 
this happens and there is a way out. To maintain a constant temperature, styrofoam boxes are used, or the bag is wrapped in many layers of newspaper. The simplest solution is to take a regular transport bag with the packed fish ready for movement, and put it inside a larger bag stuffed with crumpled newspapers. If necessary, repeat this “matryoshka” doll process several times. The fish will be reliably protected from temperature drops. If even this option is not available, wrap the fish bag in a blanket or winter clothing. Please note that at low temperatures, it is easier to carry the fish bag under your outer clothing; your body heat will keep the fish from freezing, and warm clothing will retain the heat. In hot weather, this trick won’t work, and the fish should be wrapped separately, as the task is to maintain the already low temperature.
During transportation, the properties of the water in the bag change, add to this shaking and vibration, and of course, the constantly changing environment on the outside of the bag — changing lighting, shadows, etc. In general, the fish experiences shock from all of this. It would be quite sensible to isolate the fish from stimuli whenever possible. In this case, we are talking about the opacity of the transport bag; if you cannot find an opaque bag for transporting fish, you can put the transparent bag with fish into a bag or an ordinary opaque bag, thereby isolating the fish from light stimuli.
Transporting fish from the nearest pet store to home.
Before buying fish, you need to think through many things, otherwise you will have to deal with unpleasant surprises later. Here are the most essential questions to clarify in advance: Do all fish have uniform water quality requirements? Is the pH level correct? Are there any predators in the aquarium that could attack small newcomer fish? There are many species you would never suspect of this! Medium and large aquariums should be stocked with fish living in different water layers. Namely: catfishes, loaches, and similar species for the bottom; hatchet fishes, aplocheilids, butterflyfishes, and others for the water surface. (True, there are species, including many Cichlidae, that inhabit all three zones).
So, the seller has scooped the fish out of their aquariums and placed them into a polyethylene transport bag. Whether it’s winter or summer, under no circumstances should you stroll around with your new pets for hours or leave the bag in the car without ensuring the proper temperature! It is best to head straight home.
A polyethylene bag is a temporary auxiliary tool, and the air for the fish there will not last long. Perhaps even more importantly: neither excessive heat nor excessive cold benefits 
tropical fish. If you are transporting fish during the cold season, the danger of hypothermia is especially high. In exceptional cases, you can wrap the bag in several layers of newspaper, but this is not a solution if the journey through the cold is too long. In such cases, it is better to choose styrofoam packaging. If the water in the bag is too cold, the fish’s swim bladders will immediately become inflamed, which is easily recognized by their atypical swimming style.
When the newcomers arrive home, they need to be carefully acclimatized to their new habitat. To do this, you should first float the bag on the water surface of the future aquarium for 15-20 minutes to equalize the temperature. After that, you need to open the bag, place it in a suitable vessel (so it doesn’t fall), and add aquarium water little by little (!) to the temporary “transport” container. This can also be done in another reservoir by first carefully pouring the fish into it along with the water from the bag. A few words about the reservoir: it must be perfectly clean! Residues of detergents or cleaning products can kill the fish or at least harm them! It is safest to keep a special vessel for such (or similar) occasions.
Long-distance transportation.
Bio-bags pumped with oxygen are the main method for transporting fish over long distances. Water that differs little from the fish’s daily habitat is poured into the container (it is best to take 1/3 from the aquarium and 2/3 of clean, settled water) and then the bag is filled with oxygen. The bag is tightly secured with a rubber band or electrical tape (it can be heat-sealed) and placed in a box or styrofoam container. When transporting by air, fairly spacious containers are needed: there should be approximately 50-150 grams of fish weight per one liter of water.
The bag should not be overly inflated; its surface should give slightly to pressure. Otherwise, during takeoff or due to pressure drops, it may rupture and depressurize. The allowable time for fish to stay in the transport container depends on the water temperature (for warm-water fish it should be 24-26°C), stocking density, and lighting (in the dark, fish activity decreases, and they endure stress more easily). In winter, heating should be provided — warm water warmers placed around the bag. On a train, bags of fish should be positioned so that they are subjected to as little rocking as possible.
When transporting fish by plane, keep in mind that significant pressure drops may occur during flight, which can compromise the integrity of the packaging. Therefore, it is recommended to use double bags, i.e., each bag is inserted into another bag, and they are separately and tightly secured with rubber bands. In this case, even if the integrity of the inner bag is compromised during flight (for example, due to a pressure drop), the outer bag will keep the water, fish, and oxygen inside.
During long-distance transportation of fish by car, oxygen can be dispensed with. You can add air to the water container using a battery-operated compressor. 
Pumps are available as autonomous, battery-powered units. They are exceptionally convenient for transportation. These compact, lightweight, and inexpensive devices will help you safely deliver fish even at high stocking densities and over long distances. Alternatively, you can use a bit of ingenuity and construct an aerator using a ball bladder, a medical rubber bulb, and a bicycle pump.
The main thing during transportation is to monitor the behavior of the fish — if there is a lack of oxygen, they will swim near the surface and breathe heavily. In an emergency, you can scoop water from the fish container and pour it back from a height; this will slightly oxygenate the water. Adding or changing water en route is strictly contraindicated! Do not check the condition of the fish too frequently as this disrupts the temperature regime in the container, but still do it from time to time — any deceased specimens found should be promptly removed from the water. If significant bumping is expected, it is better to place the bags vertically (mechanical water movement will have less impact on the transported organisms). During stops, it is recommended to place the bags horizontally to increase the water-oxygen contact surface area.
Here, water quality and oxygen saturation are of primary importance. Let’s start with water quality. The first thing to remember is that the less organic waste the fish excretes during transportation and the larger the volume of water provided for the transportation period, the better. Let’s look at how we can optimize these parameters.
First, the volume of the transport container. There is only one rule here — the larger, the better. Organic waste products will be less concentrated in a larger volume given the same quantities as in smaller containers. Next is the number of fish and their size: the fewer fish in the transport container and the smaller the fish in size, the less metabolic waste they produce. The next point is feeding the fish. It is recommended not to feed the fish for a few days before transportation; thus, we also reduce fish waste production during long-distance transport. Next is water temperature: the lower the water temperature, the less waste the fish will excrete and the less toxic the already present waste products will be. In addition, if any diseases develop during transport, their progression will also be slowed down. Of course, one should keep in mind the natural temperature specific to particular fish species.
The last thing worth noting is special aquarium products designed to bind toxic ammonia and convert it into a form less dangerous for aquarium fish, as well as activated carbon, which can absorb various organic substances from the water. Preparations for neutralizing ammonia and other harmful substances are called “water conditioners” and can be easily purchased in pet stores, just like activated carbon.
Long-distance transportation of fish at unfavorable external temperatures. This is the most difficult case. In such a situation, you should use the advice described earlier for short-distance transport under unfavorable temperature conditions, i.e., create a sort of thermos. However, if the transportation is long, additional cold or heat generators are indispensable.
In this case, recipes can be very diverse, ranging from additional containers filled with ice or boiling water to special chemical “warmers” that “turn on” when the temperature drops. Hot water bottles, or simply a plastic bottle with boiling water, are placed in thermal bags or styrofoam boxes usually used for carrying fish bags. Just don’t forget to wrap the hot bottle in a thick layer of newspapers or fabric to prevent overheating of nearby bags.
Safe fish transportation. What to do if fish become very cold on the way.
How to properly transport fish. What fish and plants can be transported in. 
