3y "main food" is understood the natural food vv!ach the fish, under favora'ole conditions 

 v/ill choose in preference and by vrfiich it thrives best. 



"Occasional food" means well- liked natural food, consumed \':henever the opportunity pre- 

 sents itself. This kind of food can be of relatively high nutritive value. 



"Kmercency food" is what the nane implies. It is taken in v.iien all other food fails 

 and the fish will alv.'ays thrive badly upon it, 



Accordini^ to the food chosen — in preference — the fish are to be divided into: Vegetarians, 

 Insectivores, and Predatory fishes. Among the insectivores, v.-e differentiate again — according 

 to the mode of existence of their prey — between: Plankton feeders, Bottom-life feeders, and' 

 Shore-life feeders. (In ponds, the last named ones may better be spoken of as "Vegetation 

 feeders"). 



Carp. Lehmann and Gennerich^ in 1922 cairied on investigation anent the food habits of 

 youngest carp fry. They used 6^. carp of from 0.5 to 3.9 centi:ieters in length and 17 carp 

 of from 2.3 to A.8 centimeters. The test fish came from various fisheries of Northern 

 Germany. Lehmann foiond that most of the carp, below 2.5 centimeters and vhich had not as 

 yet completely consumed the contents of their vitelline sac showed the following Intestinal 

 contents: Sizable amounts of such plankton creatures as Losmina and Anurea cochlearis and A. 

 aculesta, but in addition also similar amounts of such vegetation creatures and bottom 

 creatures as Chydorus, Alona, Simoceplialus, Cyclops, Canthocamptus and even Cypris. Formerly 

 held opinions, viz. ohat young fr^r (of carp) are strictly plankton feeders have thus been 

 exploded. The question if pure pla-Jcton is necessary for the nutrition of young carp brood 

 lias been negatively ansvrered by the findings of Lehmann, v/ho found that such brood of 0.5 cm. 

 length can already exist upon small Cyclops, Cypris and Chironomus larvae, (vegetarian or 

 shore animals) 



The complete change in evaluation principles for pond plankton has unfortunately been 

 misconstrued until recently by pond ci-lturists and also by scientists, although P. Schiemenz 

 has for a Ion;; t^.ne repeatedly pointed this out. Gennei-ich comes to the same conclusion as 

 Lehmann, ttot it must be assumt^d that the nutrition oi pond fishes in the individual pond 

 industries can be different in accordance vdth a variable supply. Tids variability should 

 not be overestL'^ated, because drainable ponds generally shov; sLrdlar conditions. Lastly 

 and worthy of mention, is that Gennerich frequently found the v;ater flea Sida and in carps 

 over A cm. also Trichoptera larvae. In brief, the carp fry are eaters of small animals 

 rather than plant eaters. Their raain nutrition consists of insect larvae and shore 

 cladoceria, and they belong to the constant eaters of shore-animals (vegetation animals). 

 Plankton is to be regarded only as opportune or emergenq^' nutrition. 



Basically, the nutrition of all larger carps is oi similar nature and gravitates in- 

 creasingly to insect larvae and somewhat from vegetation anirivals to mud ajiimals, i.e. to 

 bottom fauna. The nutrition of one-summer carp averaging 10.9 cm. taxcen on Oct. 9th from 

 a pond industry in this province, according to Gennerich, consisted for each fish mainly 

 of about 2,000-/i,000 shore cyclopidae, about 100 cladocerae of various kinds ( Sida. 

 Kurycercus . Caaptocercus. Alona . Ch^-derus ) and 10-20 insect larvae (mainly Chironomus and 

 Ephemera la rvae ) . As insect larvae may be considered to lii.ve an average caloric content 50 

 times greater than small crustacean animals, then, accordingly, loi7er shore-crustaceans and 

 insect larvae have each participated about 50 per cent in the nutrition. Nutrition of carps 

 by plankton can in no vfay be considered; the carp is not a plankton feeder r.t any age. 



Quite the sa;:ie picture v.-as shovra by 7-9.9 cm. long carps in the first year of life taken 

 in August from two ponds of a pond industry in Saxony, Tr-'o- and three-s'omner carps, examined 

 by '.Vundsch (1919), had eaten in July and also in October (before the autumnal fishing out) 

 principally Chii-ononius larvae and Ijphemera larvae, and secondarily bottom Cladocerae ( Chydorus, 

 ^ona. Camptocercus) . Lesides this, Trichoptera and Copepode larvae were occaaionally taken 

 up. iiollusks and all the remaining small animals remained in the background as nutrition 

 animals. 



This has clianred, of course, all of the opinions v.ith regard to the evaluation of plankton 



P-7tO» 



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