86 FISH FARMING: 



pulation of them where there are no spawners, my remarks 

 being intended to supplement those already made. By fully- 

 eyed ova is meant eggs which have passed through the early 

 and middle stages of incubation in al propzrly constructed 

 hatchery, and are " sown " on the nedds when they are within a 

 few days of hatching. All that is necessary is to rake level a 

 part, or parts, of the redd, or redds, of sufficient size to receive 

 the ova easily. Of course, I presume that no predatory fish 

 are on the redds, and that the protecting screens are in their 

 place below (see Figs. 2, 3, and 6). The eggs may be trans- 

 ferred from the box in which they have travelled, or from the 

 trays in one's own hatchery, direct to the redds. As a rule, it 

 is not advisable to sow more than five hundred fully-eyed eggs 

 in one " nest," and care, should be taken that none of them 

 touches another. A fairly sharp, but by no means rough, 

 current of water is best, and, if at all possible, choose a spot 

 free from the risk of a dangerous amount of sediment accumu- 

 lating. It is advisable to protect the eggs and th3 alevins 

 and fry later on under any circumstances, by the erection of 

 tanned netting screens or light galvanized wire netting 

 screens, as explained in Chapter 2. If you have any real 

 cause for fearing danger from birds or animals, such screens 

 become an absolute necessity. I have already told you to 

 make sure about the quality of the eggs, but I repeat the 

 caution. Your fully-eyed eggs should hatch before any harm 

 can come to them. As soon as the bulk of them have hatched 

 out, run a little extra water over the aJevins. You will notice 

 the little fish will " pack " together in masses. This is as it 

 should be ; it is a sure sign they are healthy. After hatching, 

 all that you can, do for the next two, or perhaps three, weeks 

 is to look to the water supply and keep the enemies of the 

 alevins at bay. 



As 1 soon as the little fish have lost the umbilical sac (see 

 chapter on rearing fry) they will commence to feed, and should 

 the redds hold a sufficiency of natural food they will look 

 after themselves. But artificial feeding, in addition, may 

 ba advisable, and this process is explained in its proper place. 



