A list of principal species of fish which are cultivated and are important from the point of view of seed production is as follows:
In Hungary, ponds are constructed on lands which are normally not utilized for agriculture and where a sufficient amount of water is available from river or creeks. Induced fish breeding is carried out in fish farms managed either by the state or by cooperatives.
Different fish species which are induced bred in Hungarian fish farms are given below (after F. Bencze and I. Fehér, 1977).
| Species | Percent contribution of the total seed production (approx.) |
| Common carp | 75 |
| Silver carp | 20 |
| Bighead carp | 8 |
| Grass carp | 5 |
| Carnivorous species | 3 |
| Others | 1 |
Though common carp reproduce successfully under natural conditions, induced breeding, i.e., hypophysation, has been found necessary for obtaining adequate numbers of fry for stocking purposes. The Chinese carps - silver carp, bighead carp and grass carp - are recently introduced species in this country and because they do not reproduce in confined water they are also induced bred with the pituitary injection.
Presently, common carp is the dominant cultivable species but it is expected that Chinese carps would be more in demand, especially once their processing and marketing are improved. The cost of production in polyculture is very much less than monoculture of common carp.
European catfish culture is also becoming increasingly important and so special attention is being paid for the propagation of this catfish. Propogation of this fish with hypophysation was started at Százhalombatta in 1974 and it is also carried out at Szarvas and other farms. The aggressiveness of both sexes increases during the spawning season/process and the resultant injuries even cause death. To avoid this during hypophysation, their mouths are sewn with strong perlon string. This does not harm the fish. Larval rearing is done in basins in the hatchery and the fry are fed tubifex until they are a few centimetres in length.
Propagation of Aspius and tench by hypophysation, has been started; however in the case of tench, the injection is given in the body cavity. Normally sturgeon are caught ripe and stripped without any injection.
Pike-perch - The natural spawning of pike-perch and the collection of the eggs are rather simple. The ripe female and male spawn easily in ponds in nests especially made from the dry roots of willows and other aquatic plants or from squares of synthetic fibre. Normally the eggs or nests are stocked in water. However, Dr. E. Woynarovich showed that the spray room techniques for incubation resulted in better survival of hatchlings, obviously because of the control of water temperature/quality. This technique is commonly practised in Hungary (Szalay, 1975).
Pike are easily propagated naturally in fishpond conditions by simulating a natural spawning environment. However, propagation by hypophysation is being carried out on a commercial scale.
Since Hungary has no natural resources of elvers, it imports them from other European markets.
Hungary has made great strides in fish seed production in the last decade and the hatchery has become an integral part of the large fish farms. The methods of rearing spawners, the identification of sex, anaesthetization, closing of the genital apertures of females of common carp, pituitary injections, ripening of the eggs, removal of sexual products and ferilization, incubation of eggs, rearing of larvae with yolk sac and feeding of the early larvae are very well known to the farm managers. Also very useful data are available on the reproductive biology of all the cultivable fishes, which are presently the best guide for hatchery management. Besides these, the most significant achievement for common carp propagation in the hatchery was the development of a simple method of treatment of eggs with salt carbamide to eliminate the stickiness. The same technique is used for Aspius and Tinca. The eggs of the catfish are treated with organic proteolytic enzyme at the rate of 0.03 g in one litre of water for 1 to 3 minutes after 24 h of their normal development so as to get rid of their stickiness. At Százhalombatta the eggs of Chinese carps are treated the same way as those of catfish, at the time of hatching of the eggs, to digest the egg shell. However, there is no reliable indicator available yet to predict the result of successful hypophysation; nor for assessing the suitability of spawned eggs for incubation.
