1130 EEPORT OF COMMISSIONER OF FISH AND FISHERIES. [30] 



The perch {Perca fluviatilis L.) is an excellent food-fish, but is hardly 

 ever raised in ponds by itself, but generally ia raising-ponds and grow- 

 ing-ponds for carp, and in ponds for crucians, in which it grows rap- 

 idly and increases enormously. As, besides small fish, its favorite food 

 is worms and insects (the same food which the carp likes), it should not 

 be placed in carp-ponds in too large numbers, unless it fetches a higher 

 price in the market than carp. 



The perch -pike {Luciopercasandra Ouv.) isesteezaed higher and fetches 

 a better price in most places than the perch ; it feeds on the same kind 

 of food, and is frequently kept in large and deep growing-poods for 

 carp. It loves deep, cool, and pure water, and a hard, sai dy or gravelly 

 bottom; and in such ponds it will increase very much, especially if 

 suitable spawning-places are i)rovided. For this purpose it may be 

 recommended to put stumps of trees with branching roots near the 

 banks, or to construct in various parts of the pond cone-shaped piles 

 of stones and gravel, measuring about 1 meter in height. In shallow 

 ponds with a soft bottom the perch-pike will also grow, provided there 

 is an ample supply of food, but they will not increase. For stocking 

 deep lakes with a hard bottom, the fry of the perch-pike is well suited. 



YIIL— KEEPING EELS TS PONDS. 



It is well known that eels only propagate in the sea, where the male 

 fish stay all the time, whilst the young fry in spring or early summer, 

 when measuring only a few centimeters in length, ascend all fresh waters 

 in enormous numbers, work their way over weirs and rocks, in order to 

 reach the upper course of the rivers, and the lakes situated near them, 

 and, are at that time without sexual distinction, but without exception 

 develop into females. These, in order to propagate the species, have 

 to return to the sea, and on these migrations, which are undertaken 

 during the summer and autumn months, the great eel-fisheries in most 

 of our rivers depend. Under no circumstances can an increase of eels 

 in fresh water be counted on ; but it is possible to facilitate their jour- 

 ney up the rivers by constructing eel- ways, and also to introduce them 

 into waters which without human aid would always remain closed to 

 them. 



From time immemorial the ascent (montee) of the young eels up the 

 rivers, which takes place in France every year in exceptionally large 

 proportions, is used for collecting large numbers of the small fish, which 

 are sent considerable distances, packed in moist grass, and used for 

 stocking ponds, marl-pits, and peat-bogs. Also in Germany large quan- 

 tities of young eel-fry, from France and Italy, have for a number of 

 years been successfully planted in ponds and lakes. When.these fish ar- 

 rive in May, they are about 6 or 8 centimeters long and 2 or 3 millimeters 

 thick, and about 1,000 of them make a pound ; but in autumn of the same 

 year they have generally reached a length of 20 to 25 centimeters, and the 



