150 NEW SOUTH WALES 



CHAPTER XIII. 



Acclimatization and Pisciculture. 



This department of natural history has assumed the most important 

 aspects of late years, and may be said at the same time to have become one 

 of the most jiopular and fashionable of zoological recreations. Accord- 

 ing to Dr. Giinther, artifical impregnation of fish ova was first practised 

 by J. L. Jacobi, a native of Westphalia, in the years 1757 and 1763, 

 who employed exactly the same method which is followed now. The 

 idea of course was to favor the natural processes, and by preventing the 

 waste of ova to restore the failing supplies of rivers, ponds, and streams. 

 The process is as follows : — The fructifying vessel, which is tolerably large 

 and with a flat bottom, is filled about one inch deep with pure water, care- 

 fully kept at the same temperature as that into which the fish resorts for 

 spawning. A full-roed healthy female fish having been selected, is taken 

 with as much gentleness as possible by two persons, who hold it in a 

 manner not likely to injure the fish, by the head and tail respectively. 

 The fish is held in an upright position, and after it has ceased struggling, 

 the roe, if it be quite ripe, commences to run from the vent, and in order 

 to obtain as much as possible the fish's sides and belly are gently rubbed 

 downwards. If the fish be large it is never worth while to press out 

 all the roe at one time. In small fishes only about half the roe is taken, 

 and the fish is jDut back again for a day or two into the reservoir, and 

 then the process is repeated. " If the eggs are quite ripe they all pour 

 out into the water following (lach other in rapid succession, like shot 

 from a shot-belt. If the eggs do not come out quite easily, give the 

 tail a gentle shake to loosen the eggs that remain in the abdomen ; but 

 recollect, if you use force you will spoil the experiment. The eggs must 

 run out quite freely." — Buckland. 



After the roe is pressed out it is spread over the bottom of the basin. 

 A male fish is then taken, and a few drops of the milt is pressed out 

 into the water. Pressure is made on the abdomen of the male in the 

 same way as the female. If the milt is ripe, it will instantly discolour 

 the water and make it white. The roe and milt are then stirred up 

 with the finger, and left for about five minutes. The milk-coloured 

 water is then poured ofiT, and fresh water gently added until the eggs 

 appear quite clear again. The milt of one male will fertilize the ova of 

 many females, and the fish can be returned to the sea or river none the 

 worse for the operation. Then the impregnated ova are either placed 

 into the breeding boxes or packed for exportation. The manner 

 of packing is this : — The boxes are about 6 inches in height and width, 

 and 2 feet long. On the bottom is a layer of damp moss, mixed Avith 

 ice (if the temperature of the season or the country require it). On this is 

 spread a damp linen cloth, over it a thin layer of ova is laid. Another 

 wet linen cloth and more moss completes the packing, which has to be 

 rather tightly fastened to prevent shaking aiad friction. In many places 

 in Europe no roe is packed until two black spots appear in the ova (the 

 eyes), because the fish bear transport better in that state. If a long 

 transit be anticipated, the ice arrangements must be different, because 

 melted ice water injures the roe. 



