Ilshbreeders have striven Tor centuries to bread these "hereditary faculties" into 

 fish, by ::ieans of selective breedjig. 



Under 2 iind 4, v.e have mentioned that a retarded 4 years old carp of good stock can 

 have the appearance of a 2 years old. But it is nevertheless of jjnportance to be able to 

 prove that a carp, apparently 2 years old, really is_ of this a[;e, This v/ould then prove 

 that such a fish is really quick -rov/lng, i.e. is of good stock. 



It is of utnost importance to the fishbreeder to be able to determine the age of pond 

 fish , in order to safeguard hinseli against the acquisition of inferior Stock. This is 

 possible by counting the "year-rings" upon the scales. 



Upon an exa-nination of the scales, we soon discover v;ell defined "zones" in the 

 arrangements of the rings. T.'e may speak of them as "summer" and "viinter" zones. 



In the "v/inter zone", the concentric rings lie closer together, v.hile the rin^s in 

 the "susuner zone" are more vddely spaced. This is explained by the higher anabolic rate 

 and through better nutrition ir: sii;:i!:ier and the lowered rate of ^rovith in v.inter, 



Exar.iination of the scales is iacilitated by first rinsinc: ti^en in a solution, pre- 

 scribed by Petrov and Petroschavj'sk?/' . as follov/s: 



2 parts of 10 per cent chloralhydrate 



1 part of concentrated picric acid (v/atery solution), 



3y this process, a clearer field of observation is obtained. 



One will notice that the rings ir. the "vinter zone" are interrupted and also branch 

 off. (See Fig. 1) 



Fig. 1, Scale of a two-soimv.cr old carpj length of fish 16 centiraeter, 

 Tv.'o summer zones and one v.'inter zone, v/ell defined and visible even 

 in lower parts, covered by skin. In its first year the carp reached a 

 length of 8 centimeter; its -rov/th in second year v/as artificially 

 i-Tipeded , 



