200 How to obtain it. 



seem to incommode the fish at first. Sooner or later the alevin 

 loses its energy, however, drops out of the pack, and, after lying 

 about for a few days it dies. I have not ascertained the exact 

 cause of this ailment, and, as far as I can make out, it has not 

 been properly diagnosed by anyone. It sometimes attacks a 

 number of fish, and sometimes only a few, and is probably caused 

 by coagulation or precipitation of albumen. Sudden changes and 

 extremes of temperature seem to produce it in the alevins in some 

 way, and it appears to attack what are otherwise healthy fish. 



Care must be taken to guard against deaths from suffocation. 

 When in the egg stage, there is, under certain circumstances, a 

 danger of the suffocation of the embryo, so there is a danger of 

 suffocation of the alevin. Such an occurrence should never 

 happen, but as it has frequently happened in the past, so it will 

 happen again unless guarded against. In the old days the loss 

 from suffocation was very great, when a variety of apparatus was 

 used that was most unsuitable for the well-being of young trout. 

 Practically, I never used anything but plain wooden boxes, but I 

 have seen apparatus that suffocated tho alevins by thousands. 

 Tanks of wood or metal, lined with slate or glass, were of common 

 occurrence, and the joints not being tight, the fish would get 

 into the crevices and behind the slates in large numbers. The 

 cause of suffocation in such places is that there is no current. 

 The same applies in any hatching boxes when, for instance, the 

 water is accidentally stopped, or if the supply be too small, 

 although it is true the fish will often live a long time under such 

 circumstances. It is really simply a question of oxygen. As soon 

 as the supply available is done death takes place. A few alevins 

 may be kept in a basin or a tumbler of water for a long time 

 without changing the water, due regard being paid to temperature. 

 I have seen a single alevin placed in a basin live three weeks 

 without a change of water. Several of my friends who have been 

 wishful to try the experiment have hatched trout ova (when well 

 eyed) in a small aquarium, and have kept a few alevins there till 

 the sa^c was absorbed, and one correspondent was successful in 

 keeping the fry after feeding for several weeks, the only precaution 

 taken being to ladle the water a little twice a day. As a parallel 

 case I may mention having to-day, as I write, heard from an eye- 



