Transportation of the common carp eggs is feasible in certain developing stage and on a limited time span which may reach up to 6–8 hours long. It is also necessary to prepare suitable facilities and equipment for the further incubation, hatching and larvae rearing in the place of destination.
The aims and advantages of the carp eggs' transportation, especially in the developing countries, are obvious. The artificial propagation of common carp needs a well trained, skilled personnel, a well selected and suitably kept breeder stock, hatchery facilities etc… which can not be provided everywhere, where otherwise the nursing of the young carps is possible. One good functioning bigger hatchery could provide many nursery places with easy transportable eggs so its action area and capacity could be increased up to the performance possibilities of the personnel and breeder stock.
The transport of the just feeding larvae (or fry) in big special transport containers or oxygen inflated plastic bags needs special equipment, has many disadvantages and dangers of damage therefore not practicable everywhere.
The transport of hard eggs of Salmonids, pike-perch and others is an old practice in many countries. The author had made some attempts to transport common carp eggs in the early sixties in Hungary with initial results, but the damages caused by Saprolegnia infection made this practice economically uncertain.
Carp egg can be successfully transported only when its development is nearing to the end of the embryo development. Practically that means to start with the transport on the last day of the embryo development calculating that arriving to the destination place after 2–5 hours further incubation the eggs should hatch. The table shows the start time of the transport by different incubation temperature of the eggs.
| Incubation temperature in C° | Start of the transport hours after the fertilisation |
| 20 | 60 |
| 22 | 50 |
| 24–25 | 40 |
| 26–27 | 20–25 |
Note : If warmer temperature can be expected during the transport it should start a few hours earlier, or made it by night, or in the early morning. The length of the transportation also should be taken in account.
Theoretical considerations
Fish egg takes oxygen by diffusion. The speed of the diffusion (the supply of the eggs with oxygen) depends on the oxygen concentration difference of the inner part and outer part of the egg shell. If this difference is great the oxygen molecules flow swift into the egg. The oxygen supply slows down when this concentration difference becomes small that means the oxygen concentration on the egg surface diminishes. Diffusion of the oxygen (and other gases) can occur only trough wet egg shell i.e. a thin film of water has to be remaining on the egg surface. No diffusion can occur through dry egg shell.
The air has about 20 times more oxygen molecules as the well aerated water has; therefore the transport is very convenient in an air surrounded place provided the eggs surface remains wet during the entire transport. The other very important precondition is that the eggs have to be treated preventively with malachit-green or other chemicals effectual enough to prevent Saprolegnia development during and after the transport.
Practical solution
Wooden, wire-mesh bottomed (mesh 1-1.5 mm) flat boxes were used (size 40 × 20 × 7 cm). Each box was lined with a piece of well moistered flannel of cotton such a way, that the sides of the textile can cover the eggs and overlap each other. The size of the textile was 0.9 × 0.9 m. The eggs are placed carefully on the textile sheet in 0/ 1–2 cm thickness and covered with the remaining part of the wet textile. About one liter eggs can be placed in such a box. A row of boxes can be placed over each other leaving about 2 mm gap between the boxes. Now the boxes are placed in a carton which bottom is covered with short bamboo branches with leaves or other hard, springy grass, to provideair from below as well. A space has to remain too around the boxes. This space is also kept with springy bamboo branches. Care should be taken that the boxes remain in place during the transport. A wet plastic foam sheet is placed on the top of the boxes to provide further moisture for the eggs from above.
The eggs should be treated regularly from the beginning of the embryo development preventively with malachit-green. Short before the transport the last treatment has to be made, and after the treatment the eggs should be washed throughly in the incubation jars.
Reaching the destination place the eggs are packed out and placed immediately in a hatching jar used for hatching carp eggs and rearing the larvae.
Simple installation for receiving the transported carp eggs can be erected everywhere, where continuous water supply is possible, and with about 1 m level difference. Such jars can be placed for example on the dry side of a pond dike. Water can be supplied from the pond by siphooning or placing a closable tube in the dike's body. A filter cylinder or other filtering device has to be used to keep off the bigger plancton organisms, small fishes, enemies, debris, from the jars. 1–1.5 liter egg can be placed in a 50 l jar and 2–2.5 liters in 200 l jar. The eggs will hatch soon and the further handling on the larvae is the same as it was described by the hatchery activities.
If jars are not available in the destination place the eggs can be hatched in hatching boxes, of course with less efficiency and greater possibility of losses. The eggs shall be placed on the bottom of the hatching box possibly in a thin layer. About less than 1 liter egg can be placed in one hatching box of 1.2 × 1.2 m.
