Modem carp fisheries conduct their enterprises according to the "grading" system 

 and wldch has supplanted the old-time "Femel" system most everywhere. 



Under this old-time method, fish of all ages were kept in one and the same pond, 

 were even left to spawn in them. Fish of marketable sizes were caught as needed, with 

 the result that in the end only the least worth-while fish remained to spawn. Under such 

 conditions, the whole stock, of course, would gradually decline, more and more. 



Under the new "grading" system, the different grades (according to age) are kept 

 separately. In this way the growth of the individual fish can be continuously studied 

 and watched. The rotation is normally a three year one. A four year rotation increases 

 the cost of maintenance for an additional year without adding anything to eventual profits. 

 Conditions are more favorable only when the fish have been strongly retarded in the first 

 two years. In the two year rotation there is too great a risk in obtaining yearlings 

 which must be of about 250 g weight. In the fishing out there will soon be too small and 

 too few yearlings. Besides this, in the two year rotation, the yield per unit surface 

 is decreased by the reduced stock density necessary for the high individual growth. 



In regard to the methods of race breeding much iaPtill to be desired. Incidentally, 

 Baur has rightly said that fish breeders should learn from horticulturists and that the 

 obtaining of positive qualities in pond fish breeding could not be expected. The fish 

 must not be judged by appearance but by the results to be expected of their progeny. 

 Similarly as in plant breeding, this requirement can be easily fulfilled since the 

 progeny of the fish is so numerous. Only the best of the numerous offspring are selected 

 and hybridized. 



Proper selection is to be begun amrmg the yearlings of one and the same pond ^ express- 

 ed elsewhere in this book. The fish of such a pond must have been kept separated from the 

 others. Only in this way can it be avoided that the best fish will be gradually taken 

 out, and that a badly growing 3-year-old fish will in the end be mistaken for a good 

 growing 2-year-old, 



Cerna.jev and Nowak have objected to such a procedure upon the ground that the bodily 

 proportions of yearlings differ from those of older fishes, and would therefore not permit 

 a reliable Judgement. This is meaningless as they should be valued first as to results 

 and secondly as to form. 



At the first selection, ten times more yearlings are chosen than will be needed for 

 spawning (or spawners). These fish must only be kept together with older fish so as to 

 remain easily distinguishable, A permanent marking would be still better, of course, 

 but such a method has not been found as yet. 



In the fall of the second year 50 percent of the best of these carp are again select- 

 ed, in the third year 25 percent of the best of these, and finally in the fourth year 10 

 percent of the best three-year-olds. The remainder goes to market. 



The so selected fish are kept as prospective spawners (parent fishes) and are broiight 

 together in ponds with young fish (about 4 to 8 prospective spawners per hectar) and are 

 left to spawn from the 5, to 7. year. 



The question has been raised at times, if future spawners are to be fed - or not. 

 Since noticeable injury to spawners, from feeding them has not been observed, so far, I 

 am of the opinion that light feeding, toward the end of the first summer is indicated, 

 or at least not to be objected to. Only in this way can it be found out if carps, aside 

 from being good natural feeders, will also assimilate artificial food and show this by 

 increased growth. Feeding in later years has only disadvantages. It is quite possible 

 that the resistance of the offspring is lowered thereby. 



Still more important is the choice of spawn ponds. These ponds must be rich in 

 natural food and must also be not too small, Cnly then will the sex products ripen well 

 (according to observations by Schau), which perhaps is the effect of the "space factor" 

 coD^lex, referred to previously. 



77 



