FISH CULTURE. 933 



the same temperature as the water before unpacking them. This will surely kill the eggs in 

 a few hours. Leave them in the original package until a few hours before you are ready to 

 place them in the troughs. Then take out the tins and set them over or near the troughs, 

 which will reduce or raise the temperature enough. Then empty the box into a tin pan full 

 of water taken from the trough, pick out as much moss as you can readily with your fingers 

 or nippers, and wash off the nest in the manner shown in directions for washing eggs here 

 after. 



If the eggs have had decent treatment on the way, that is, not thrown about roughly or 

 set near a red -hot stove, you should find very few dead eggs in the boxes not more than 

 ten or twelve in one thousand. Should the eggs be found, on opening the box, to run 

 together in lumps instead of being evenly distributed, and turned to a dead white or milky 

 color, it shows rough usage on the way. 



Temperature of Water and Time of Incubation. The length of time required 

 to hatch out the eggs depends upon the temperature of the water. A general rule sufficiently 

 accurate for all practical purposes is this: At fifty degrees trout eggs will hatch out in fifty 

 days, each degree colder takes five days longer, and each degree warmer five days less. The 

 difference, however, increases as the temperature falls and diminishes as it rises. The best 

 temperature for hatching is between thirty-five and forty-five degrees. We are inclined to 

 believe that the fish hatched at a temperature of about forty-five degrees, and taking from 

 seventy to seventy-five days to hatch, are stronger and longer lived than those hatched in 

 fifty days at fifty degrees. It may be well also to note that the eggs earliest taken produce 

 the best fish. The water of a spring can be reduced in temperature in winter by letting it 

 run for a short distance exposed to the open air, or it may be collected in a pond and the 

 supply either drawn from the pond or the stream, whichever is regarded as the most 

 desirable. Another reason for delaying the hatching of trout is to bring them well into 

 spring before they are turned loose, as at that time they can get more abundant food than 

 they could earlier. 



Growth in the Egg. A great mistake is often made where eggs are to be dis 

 tributed in retaining them too long after impregnation. This is sometimes done for 

 convenience in shipping, and sometimes with a view of shortening the operation of hatching 

 in the hands of the person receiving them, but it is all wrong. 



About the twentieth day the young fish can be plainly observed in the egg. Put a few 

 eggs in a small phial, and with a magnifying glass the formation of the fish can be easily 

 seen. Fish farmers should send the eggs away at this time. Some of the eggs are not 

 impregnated, and at this stage of growth may easily be distinguished from the others. The 

 dead eggs will turn to a milk or a pearl white color, and should be removed with the nippers 

 as fast as they are discovered. If left in the trough a fungus growth forms upon them, 

 which extends to the other eggs in the immediate vicinity and kills them. Care should be 

 taken, in using nippers, not to hurt the other eggs, and to do this the bad egg should be 

 feathered entirely separate from the rest; a very slight blow or jam from the nippers will be 

 sufficient to destroy their vitality. Rats and mice in the hatching house often destroy many 

 eggs; they are very fond of them, and, going into the troughs to get them, will destroy with 

 their feet many more than they eat. A wire screen, or boards laid over the troughs, will 

 keep them out; but it is a much cheaper way, and just as effectual, to keep them down by 

 traps or poison. The eggs should be feathered over occasionally, so that their whole surface 

 may be exposed to the action of the water. 



Hatching Trout and Salmon. After the eggs have lain in the water from fifty to 

 seventy-five days, according to the temperature, the trout will begin to make their appear 

 ance, the egg appears to be endowed with life, and the motions of the trout inside &quot; kicking &quot; 

 against the shell to force their way out can be plainly perceived without the use of a micro 

 scope. At length the trout forces his way through, head first or tail first, those that hatch 

 head first always dying, however, and the useless shell floats away down stream. The trout 

 is then about one-half an inch long, and the body proper as thin as a needle; the most 

 prominent features being a pair of eyes, huge in comparison with the rest of the body, and a, 

 sac nearly as large as the egg. This sac is attached to the belly of the fish, and contains food, 

 which the fish gradually absorbs. If the fish are hatched in fifty days, the sac lasts about 

 thirty ; if in seventy days, about forty-five. At this period of their lives they will work 

 down into the crevices of the gravel and along the sides of the troughs and stay there, nature 

 seeming to give theui the instinct at this weak and defenceless period of their lives, when 



